Fruiting body subglobose, cushion-shaped, to turbinate, 6.0-11.0 cm tall, 7.0-13.0 cm broad, abruptly tapered towards the base, sometimes with a root-like attachment to the substrate; exoperidium persistent, thin, less than 1.0 mm thick, glabrous, pallid to pale greyish-tan, basal area dull purple-brown in age; endoperidium 2.0-3.0 mm thick, punky, brittle; gleba cream-colored, then ochre, eventually dull yellowish-brown, occasionally tinged olive, powdery; subgleba and sterile base absent; fruiting body opening by splits or polygonal fractures; odor of mushrooms; taste untried.
Spores 4.0-6.0 x 3.5-5.0 µm, subglobose to ovoid, mostly the latter, smooth, with a central oil droplet and a short, < 1.0 µm pedicel; spores dull yellowish-brown to tobacco-brown in mass; capillitium with round to oval pits.
Solitary or in small groups in native grasslands or dry, open areas; fruiting shortly after the fall rains, again in the spring; known from coastal locations but probably occurs elsewhere at low elevations; occasional.
Edible and good. Should be eaten only when young and firm with the gleba still pure white.
The principal fieldmark of this Calvatia, as the species name suggests, is a relatively thick peridium. Mycenastrum corium and Bovista pila are similar, though usually smaller. They mimic Calvatia pachyderma in lacking a sterile base, opening by cracks, and fruiting in grass. Mycenastrum corium can be differentiated by a tough, leathery, not brittle peridium, and a firm, not powdery gleba. It also has a distinctive capillitium, the main branches giving rise to short, antler-like stubs. Bovista pila can be distinguished by a thin, parchment-like endoperidium, usually with a purple-brown metallic sheen, and a capillitium composed of thick-walled, more or less dichotomously branched individual elements.