A large, deep-water species with a chalky, friable shell and thick tan to black periostracum, which has long posterior projections. The ligament is external and projecting. Length to 150 mm.
Rarely taken alive, this species is frequently found in compact clay substrata that are difficult to sample, but in the right locations hundreds of dead specimens, consisting mostly of periostracum, may be taken in a dredge haul.

Sitka, Alaska (57.1 °N) [NMC], to the Golfo de California and south to near Isla de Afuera, Perú (6.7°S) [LACM], in 400-4,100 m; also in the western Pacific off Mys Olyutorsky (60°N). Common in the diet of Anoplopoma, the sablefish. Reported as early as the Pliocene in the eastern Pacific and the Asian Miocene.