The earth star fungus is classified as a type of "stomach fungi" and is related to puffballs, though it differs in having three layers that allow it to move. The fruiting body is a sac filled with dry spores that either releases spores as the inner layer wears away or forms an opening at the top; when struck by raindrops, spores are pushed out and the sac returns to its original shape. When young, the earth star looks like an onion before the outer layers split open into star-like rays holding the central spore-filled sac.