It has a depressed shape with about six whorls, carrying at the shoulder six blunt, large, projecting tubercles.

Outside of this ridge in the young it is constricted by a row of pits between which and the periphery are some obscure spirals in some specimens.

The outer margin of the aperture, which is very thick, is modified by the umbilical keel and other sculpture.

The operculum is multispiral, with the external edges of the whorls fringed, very concave, and showing hardly any calcareous deposit.

This species is usually covered with Polyzoa, Lithothamnion, and other adherent matter, which obscures its appearance, but the shell itself is so rude, spongy, and bleached in appearance that the actual surface is often discriminated only when examined with a lens.