Lycogala epidendrum, commonly known as wolf's milk or groening's slime, is a cosmopolitan species of myxogastrid amoeba which is often mistaken for a fungus.

The aethalia, or fruiting bodies, occur either scattered or in groups on damp rotten wood, especially on large logs, from June to November.

When conditions change, the individuals aggregate by means of chemical signalling to form an aethalium, or fruiting body.

Colour is quite variable, ranging from pinkish grey to yellowish brown or greenish black, with mature individuals tending towards the darker end.

The pseudocapillitia, sterile elements in the spore mass, are long, flattened, branching tubes with transverse wrinkles and folds.