How does a ripe earthball release its spores?

Its skin tears open and wind and rain carry them away

What should you do if someone may have eaten part of a wild mushroom?

Tell an adult straight away and get medical advice

Common Earthball

scleroderma citrinum

Earthballs (genus Scleroderma) are round, stemless fungi with a tough, scaly skin and a dark mass of spores inside. The common earthball, Scleroderma citrinum, grows on acid, sandy soils in woods across Europe and North America, where its threads team up with tree roots. It is poisonous, and although it looks like a puffball, it is more closely related to boletes.

Also known as Pigskin poison puffball, Citrine earthball, Earth ball

Earthball powers

8–13 µm per spore, far too small to see
When an earthball is ripe, its tough skin tears open. Wind and rain then carry clouds of dark spores out into the wood.
- There is no ready-made hole: the ripe skin splits into a large, irregular opening.
- In dry spells the wind blows the spores out; in wet weather the rain washes them out.
- Each spore is a spiny ball 8–13 µm across, two to three times as wide as a common puffball’s (3.5–4.5 µm).
- Don’t sniff or play with spore clouds. In 1994, eight teenagers in Wisconsin, USA, needed a doctor after breathing in lots of puffball spores.
Width of one spore
Common earthball8–13 µm
Common puffball3.5–4.5 µm
Bars show the largest sizes
Sources [1, 3, 6, 13]
3 stages pale, purple-black, spore dust
Look inside with x-ray vision. The spore mass starts pale and firm, turns purple-black with white marbling, then crumbles into dust.
- Young: whitish flesh, sometimes with a pink-purple tinge.
- Maturing: purple-grey to purple-black, marbled with white veins, still firm.
- Ripe: a blackish to dark brown, powdery mass of spores.
- Young puffballs are pure white inside. An earthball never is, which is one of the best clues for experts.
Sources [1, 2, 3]
4–12 cm across when full-grown
Earthballs push up from July and swell through late summer and autumn, darkening inside and splitting open as the year cools.
- Fruiting season in Britain and Ireland runs from July to early December.
- Full-grown common earthballs are usually 4–12 cm across and 3–6 cm tall.
- North American guides describe smaller ones, about 2–5 cm across.
- They grow alone, scattered or in groups, often on moss, sandy paths and the banks of forest ditches.
Width across
Common earthball4–12 cm
Common puffball3–6 cm
Bars show the largest sizes
Sources [1, 2, 3, 6]
Up to 80% of a plant’s N and P can come via mycorrhizal fungi
Underground, the earthball’s threads grow out from its base and wrap the tips of tree roots. This partnership between a fungus and a root is called a mycorrhiza.
- Almost all land plants team up with mycorrhizal fungi. Across all kinds, these fungi can supply up to 80% of a plant’s nitrogen and phosphorus.
- The common earthball partners oaks and other trees. Earthball strains from chestnut woods formed mycorrhizal roots on chestnut seedlings in the lab.
- Earthball relatives that partner many kinds of trees are spread more widely, which suggests being a generalist helps a fungus travel.
- Earthball genomes have only a small set of genes for digesting plant walls, a sign of living as a partner rather than a rotter.
Sources [2, 14, 15, 16]
1–21% of a plant’s yearly growth goes to its root fungi
Fungi can’t make food from sunlight. The tree sends sugars down to the earthball’s threads, and the fungus pays back with nutrients from the soil.
- In culture studies, plants handed 1–21% of their total yearly production to their mycorrhizal fungi.
- Slow-growing plants on poor soils gave the biggest share.
- In return the fungi deliver nitrogen and phosphorus. Around oak and earthball roots, bacteria also help free minerals from rock.
- Whether these fungi bring trees much water is less clear: studies disagree.
A plant’s yearly growth 100% of its net production
Up to 21% to its root fungi
Culture studies; the range was 1–21%
Sources [11, 12, 14, 17]
1–3 mm thick rind
Scleroderma means “hard skin”. The thick, leathery rind keeps the spores sealed inside until they are ripe.
- The rind of a fresh common earthball is 1–3 mm thick. Experts warn that measurements taken from dried museum specimens can mislead.
- Cut or bruised, the skin often blushes yellowish, pinkish or red.
- Coarse, warty scales cover the surface, darker than the skin between them.
Sources [1, 2, 3, 7]
1 host the parasitic bolete grows on nothing elseStill debated
Sometimes a small bolete mushroom sprouts straight out of a common earthball. Pseudoboletus parasiticus grows on this species and nowhere else.
- Its cap is 2.5–7 cm across, yellowish brown with a hint of olive, on a stem 4–8 cm long.
- It grows alone or in small clusters in summer and autumn, in Europe and eastern North America.
- Both fungi belong to the Boletales, so the bolete is growing on a distant relative.
- How it feeds, and how much it harms the earthball, is still not well understood. Some experts question whether it is a true parasite.
Sources [1, 3, 10, 18]
123 times closed spore balls evolved separately
Earthballs look like puffballs, but they are not close relatives. The closed spore-ball shape has evolved again and again in different fungus families.
- Earthballs belong to the Boletales, with boletes. Common puffballs belong to the Agaricales, with gilled mushrooms.
- In a family tree of 8,400 mushroom-forming fungi, scientists counted 123 separate origins of these closed, ball-like shapes.
- Clues: earthballs have a thick, scaly skin, no hole on top and are never pure white inside. Puffballs are pear-shaped and open by a small hole.
- Earthballs are poisonous. Never eat a wild fungus you find, wash your hands after touching one and tell an adult if someone may have eaten some.
Sources [3, 6, 7, 19, 20, 21]

Tap a pin on the model or a part below.

1–3 mm thick rind
- The name Scleroderma comes from Greek words meaning “hard skin”.
- In a fresh common earthball the rind is 1–3 mm thick and whitish inside. Cut it and it often blushes yellowish or reddish.
- The skin keeps the spore mass sealed in until the earthball is ripe.
Sources [1, 2]
citrinum means lemon-yellow
- The skin is dirty yellow to ochre-brown and covered in coarse, warty scales of irregular shapes and sizes.
- The scales are darker than the skin between them, a bit like crocodile skin.
- Its species name, citrinum, refers to the lemon-yellow tinge of most common earthballs. Field guides compare the whole ball to a warty potato.
- Its skin holds unusual pigments, including one named sclerocitrin. Chemists found the same rare family of pigments in a bolete, the peppery bolete.
Sources [1, 2, 3, 4, 5]
Never pure white inside
- The inside, called the gleba, is where the spores form.
- In a young earthball it is firm and whitish, sometimes with a pink-purple tinge.
- It soon turns purple-grey to purple-black, marbled with white veins, and ends as a dark, dusty spore powder.
Sources [1, 2, 3]
8–13 µm across, one spore
- Each spore is a tiny sphere covered in spines, 8–13 µm (thousandths of a millimetre) across.
- Ridges join many of the spines into a net, although the net is sometimes only partial or missing.
- A common puffball’s spores are much smaller: 3.5–4.5 µm.
Sources [1, 2, 6]
Wind + rain carry the spores away
- An earthball has no ready-made opening. When it is ripe, the skin tears into a large, irregular hole.
- In dry spells the wind blows the spores out; in wet weather the rain washes them out.
- Puffballs are different: a small round hole opens at the top.
Sources [1, 3, 6]
- Earthballs have no real stem. The common earthball is pinched where it meets the ground.
- Its base is tied into the soil by whitish to yellowish cords of fungal threads, called rhizomorphs.
- Some other earthballs that live in sand grow a thick, stem-like base to lift themselves above the shifting sand.
Sources [1, 2, 7]
10 mg/L cadmium one strain grew through
- The ball is only the fruiting body. The fungus itself is a web of fine threads in the soil, the mycelium.
- On beech roots, a close relative, the scaly earthball, forms silvery-white sheaths with lots of rope-like cords reaching into the soil.
- In a lab test, a common earthball strain from mine waste kept growing normally at the highest cadmium level tested, 10 mg per litre.
Sources [8, 9]
1–21% of a plant’s yearly growth paid to its root fungi
- The common earthball is mycorrhizal: its threads wrap the tips of tree roots and trade with the tree.
- It was first described growing with European oaks and also partners other broadleaved trees and conifers.
- Bacteria living around oak and earthball roots in poor, acid forest soil are especially good at breaking down minerals.
Sources [2, 10, 11, 12]
2.5–7 cm cap of the parasitic bolete
- Pseudoboletus parasiticus is a small bolete that grows right out of common earthballs, alone or in small clusters.
- It grows on the common earthball and nowhere else.
- How exactly it lives off its host is still not well understood.
Sources [2, 3, 10]
- The common earthball has an unpleasant, rubbery smell, a bit like gas.
- Some popular fact lists say it smells of raw potato, but the expert guides we checked describe gas. The potato comparison is about its looks.
Sources [1, 3]

Real earthballs

Photos from Wikimedia Commons. Some of them can repaint the 3D model.

A common earthball in a German woodPhoto: Norbert Nagel, CC BY-SA 3.0
Coarse scales on the tough skinPhoto: Holger Krisp, CC BY 3.0
Ripe earthballThe skin has torn into a large, irregular hole, and the inside has turned into purple-black to dark brown spore powder.Wind and rain carry the spores awayRipe and splitting open: about to release its spores. Photo: Norbert Nagel, CC BY-SA 3.0
Ripe earthballThe skin has torn into a large, irregular hole, and the inside has turned into purple-black to dark brown spore powder.Wind and rain carry the spores awaySpores spreading through cracks in the skin. Photo: Dat doris, CC BY-SA 4.0
Ripe earthballThe skin has torn into a large, irregular hole, and the inside has turned into purple-black to dark brown spore powder.Wind and rain carry the spores awayCut open: the black spore mass of mature earthballs. Photo: Hans-Martin Scheibner, CC BY-SA 3.0
Fully ripe: the inside has turned to spore powderPhoto: Hans-Martin Scheibner, CC BY-SA 3.0
A good year: hundreds of earthballs in a Dutch forestPhoto: Henk Monster, CC BY 3.0
With parasitic boleteSmall yellowish-brown boletes, caps 2.5–7 cm, growing straight out of the earthball.IUCN Red List: Least ConcernParasitic boletes growing on their only host. Photo: Hans Hillewaert, CC BY-SA 4.0
With parasitic boleteSmall yellowish-brown boletes, caps 2.5–7 cm, growing straight out of the earthball.IUCN Red List: Least ConcernPseudoboletus parasiticus on a common earthball. Photo: Lukas Large, CC BY-SA 2.0
Common puffball (to compare)Pear-shaped, 3–6 cm across and 4–9 cm tall, with a pale, spiny skin and a small hole that opens at the top.Lives on dead plant matter instead of partnering treesFor comparison: common puffballs, which are not earthballs. Photo: Ryan Hodnett, CC BY-SA 4.0

Earthball by the numbers

Measured by mycologists and recorded by naturalists, with comparisons you can picture.

Size: 4–12 cm; across and 3–6 cm tall in Britain; North American ones are often 2–5 cm⁠[3, 2]
Rind: 1–3 mm; thick, whitish inside, blushes when cut⁠[2]
Spore width: 8–13 µm; spiny, net-patterned spheres⁠[1, 6]; Earthball spore13 µmCommon puffball spore4.5 µm
Season: Jul–Dec; July to early December in Britain and Ireland⁠[1]
GBIF records: 85,784; records worldwide, 77,486 of them in Europe; 53% of all records for the genus⁠[18, 24]
Earthball species: ≈25; described in the genus Scleroderma, with new ones still being found⁠[7, 25]
Family age: 66+ million yrs; the earthball group (Sclerodermatineae) began in the late Cretaceous⁠[16]
Hospital cases: 4.7%; of mushroom-poisoning cases at one German university hospital were common earthballs⁠[26]
Sugar share: 1–21%; of a plant’s yearly growth goes to its mycorrhizal fungi (culture studies)⁠[12]
Ball shapes evolved: 123 times; separate origins of closed spore balls like earthballs and puffballs⁠[20]

Earthball myths and facts

Lookalikes, old stories and popular claims, checked against the evidence.

0 of 8 answered

“An earthball is just a kind of puffball.”
“Earthballs are fine to eat, like puffballs.”
“An earthball’s inside gives it away.”
“Earthballs have a hole on top to puff out their spores.”
“Earthballs smell like raw potato.”
“Earthballs help trees.”
“Another mushroom can grow on an earthball.”
“Earthballs were once passed off as truffles.”

Earthball records

Superlatives with numbers behind them.

Only home
1 host
Common earthball
The parasitic bolete Pseudoboletus parasiticus grows on the common earthball and nowhere else.⁠[3, 10]
Most-recorded earthball
85,784 records
Common earthball
More than half of the 160,942 records for the whole genus Scleroderma on GBIF.⁠[18, 24]
Most reinvented fungus shape
123 origins
Closed spore balls
In a family tree of 8,400 mushroom-forming fungi, closed spore balls such as earthballs and puffballs evolved separately 123 times.⁠[20]
Named at the starting line
1801
Christiaan Persoon’s 1801 book
Persoon described the common earthball in Synopsis Methodica Fungorum, the official starting point for naming this kind of fungus.⁠[2, 1]
Old family line
Late Cretaceous
Earthball group (Sclerodermatineae)
Scientists estimate the group began in the late Cretaceous, more than 66 million years ago, when dinosaurs still lived.⁠[16]
Metal-tough threads
10 mg/L cadmium
A common earthball strain
Grown from mine waste, it kept growing normally at the highest cadmium level tested, while two strains of another fungus slowed to half growth at 4.8 and 6.9 mg/L.⁠[9]

An earthball’s year

What happens above and below the ground, from summer into early winter (Britain and Ireland).

Spring and early summer
Trading underground
Below ground, the mycelium is linked to tree root tips, trading nutrients from the soil for the tree’s sugars.⁠[2, 12]
July
First earthballs
Firm, yellow-brown balls push up on moss, sandy paths and the banks of forest ditches.⁠[1, 3]
Late summer
Darkening inside
The pale inside turns purple-black with white marbling as the spores form.⁠[3, 2]
Summer to autumn
Bolete visitors
On some earthballs, small parasitic boletes sprout from the skin.⁠[10]
Autumn
Skin splits
Ripe earthballs tear open, and wind and rain carry the dark spores away.⁠[3, 1]
Early December
Season ends
The last earthballs of the year finish as winter begins.⁠[1]

Staying safe around earthballs

Earthballs are poisonous, but a few simple habits keep everyone safe. Admire them, photograph them and leave them where they grow.

Don’t eat
any wild fungus
Earthballs are poisonous and are often mistaken for edible puffballs. Never eat a mushroom you find.⁠[3, 26]
Don’t sniff
spore clouds
Breathing in lots of puffball spores has made people ill, so keep your face away from dusty, ripe fungi.⁠[13]
Wash
your hands
If you touch a fungus, wash your hands before eating, and keep your fingers away from your mouth and eyes.
Tell
an adult
If someone may have eaten part of a mushroom, tell an adult straight away. A photo or a piece of the mushroom helps experts work out what it was.⁠[4]
111 / 999
in the UK
Call NHS 111 if you’re not sure whether something swallowed, touched or breathed in is harmful. Call 999 if someone is seriously unwell.⁠[21]

This page is for learning, not medical advice. Outside the UK, call your local poison centre or emergency number.

Earthball vs puffball vs truffle

Three kinds of fungus balls that people mix up.

Common earthball vs common puffball vs black truffle
	Common earthball	Common puffball	Périgord black truffle
Fungus group⁠[18, 6, 27]	Boletales, with boletes	Agaricales, with gilled mushrooms	Ascomycetes (sac fungi)
Where it grows⁠[3, 23, 27]	On the ground in woods, often on moss or sandy soil	On the ground in woods, by roadsides and in towns	Underground, in chalky soils of southern Europe
How it lives⁠[2, 23, 27]	Partner of tree roots (mycorrhizal)	Recycles dead plant matter	Partner of tree roots (mycorrhizal)
How spores get out⁠[3, 1, 6, 27]	Skin tears open; wind and rain	Small hole on top; raindrops squeeze out puffs	Forms underground (not covered here)
Spore width⁠[1, 6]	8–13 µm, spiny	3.5–4.5 µm	Not covered here
Food?⁠[3, 6, 27]	No: poisonous	Young ones are eaten by experts; lookalikes are risky	A prized delicacy, sold by experts

Never eat any wild fungus you find. Lookalikes fool people every year.

Is the earthball endangered?

The common earthball is the most-recorded earthball in the GBIF database, but like many fungi it has never been formally assessed.

IUCN Red List

Not Evaluated (NE)

Trend unknown

The IUCN Red List has not assessed Scleroderma citrinum. It is very common: GBIF holds 85,784 records, 77,486 of them from Europe.⁠[18, 28]

Not evaluated (IUCN status checked via GBIF, 2026)

Threats

Changing forests
Mycorrhizal fungi depend on their host trees. Across European forests, the environment and the host trees explain most of the variation in which of these fungi are found.⁠[29]
Hungrier trees
Many European forests show worsening tree nutrition. Scientists suspect changes in mycorrhizal fungi may be part of the reason, but this is still being tested.⁠[30]
Unknown trend
Without a Red List assessment, nobody knows whether earthball numbers are rising or falling.⁠[18]

What’s helping

Record sightings85,784
Photos and records shared by naturalists build maps like GBIF’s. Snap it, don’t pick it.⁠[18]
Earthballs at work
A tropical earthball, Scleroderma bermudense, partners seagrape trees that are planted to stabilise and restore damaged coastal sand dunes.⁠[31]
Stronger seedlings1.13–2.48×
Hazel seedlings partnered with another earthball, Scleroderma bovista, grew roots 1.13 to 2.48 times bigger in length, area and volume than seedlings without it.⁠[32]

Neighbours with a status

Parasitic bolete (Pseudoboletus parasiticus)Least Concern
Least Concern on the IUCN Red List. It depends entirely on the common earthball.⁠[22, 3]
Common puffball (Lycoperdon perlatum)Least Concern
Least Concern on the IUCN Red List.⁠[33]

Earthball quiz

12 questions. Every answer is somewhere on this page.

Question 1 of 12Score 0

What does the name Scleroderma mean?

Common Earthball field notes

Diet, food web, safety and badges from the Snappit field guide.

Ecological connections

OakSymbiotic with
Helps oak trees get water and nutrients from the soil.
Scots PineSymbiotic with
Forms beneficial root connections, aiding pine tree growth.
Black SlugEaten by
Slugs occasionally nibble on its developing fruiting body.
Ground BeetleEaten by
Some beetles might feed on its decomposing tissues.

Safety

Danger 2/5 · Low

Do not touch or eat wild mushrooms without adult supervision.

Traits

Collections

Fungi

Classification

Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Boletales
Family: Sclerodermataceae
Genus: Scleroderma

Also known as

Pigskin poison puffball · Citrine earthball · Earth ball · Common Earthball Fungus · Earthball Mushroom · Scleroderma

Sources for these earthball facts

33 studies and references · checked Oct 16, 2026

Frequently Asked Questions

How to identify Common Earthball?

Compare the cap shape, the underside, the stem and base, and whether the fungus grows on wood or soil. Some fungi have gills, others pores or teeth. A cap seen only from above often hides the most useful features. Mushroom Identifier: upload a photo and compare the visible details.

Is Common Earthball edible?

poisonous

How big is Common Earthball?

3-10 cm

Where is Common Earthball usually found?

Forests, grasslands, and sometimes gardens.

What does Common Earthball grow on?

soil

When is Common Earthball in season?

Summer to Fall

What color are Common Earthball spores?

Olive-brown to purplish-brown

Is an earthball poisonous?

Yes. The common earthball is poisonous and causes mushroom poisonings in the UK and elsewhere every year. It is not usually described as deadly, but it should never be eaten.

How can you tell an earthball from a puffball?

Earthballs have a thick, warty, yellow-brown skin, no hole on top, and are never pure white inside: they turn purple-black early. Common puffballs are pear-shaped and open by a small hole at the top. Even so, never eat a wild fungus you find.

What is inside an earthball?

The gleba, a mass of developing spores. It is whitish when young, turns purple-black with white marbling, and ends as a dark, dusty spore powder.

Is it safe to touch an earthball?

It’s best not to pick wild fungi, and if you do touch one, wash your hands afterwards. Keep your face away from the dusty spores of ripe ones. If you’re worried someone has swallowed, touched or breathed in something harmful, in the UK call NHS 111, or 999 if they are seriously unwell.

What is the mushroom growing on an earthball?

It is probably the parasitic bolete, Pseudoboletus parasiticus. It grows only on the common earthball, alone or in small clusters, in summer and autumn.

Are earthballs related to truffles?

Not closely. Earthballs belong to the Boletales, with boletes, while truffles are ascomycetes that form their fruiting bodies underground. Earthballs were reportedly once passed off as truffles.

Where and when do earthballs grow?

On acid, sandy soils in woods, often on moss, forest paths and the banks of ditches, near the trees they partner. In Britain and Ireland they appear from July to early December.

How does an earthball get its food?

Fungi can’t use sunlight. The earthball’s threads partner tree roots: the tree sends down sugars, and the fungus delivers nitrogen and phosphorus from the soil. In culture studies, plants gave 1–21% of their yearly production to such fungi.