Puffball, any of about 270 species of globular fungi, order Lycoperdales, that proliferate in moist humus or on decaying tree stumps. The mature fruiting body becomes leathery and dry and, when disturbed, emits puffs of powdery spores through an opening at the top. The giant puffball, Calvatia gigantea, one of the many species that are edible when immature, grows as large as 1.2 m (4 ft) across. Earthstars, the leathery covers of which peel back in the form of stars, are also puffballs.