The shell is thin, smooth and fragile, and consists of two to three whorls with a short spire.

The dorsal surface of the mantle bears tubercular projections, the margins are thickened and there is a siphon-like extension at the front.

The colour is variable, varying from grey to lilac, yellowish, buff or orange, sometimes with black flecks.

These colourings make it difficult for potential predators to detect the molluscs, and another defensive mechanism is acid-secreting glands in the dorsal epidermis that make the molluscs distasteful to fish.

The larvae hatch after about three weeks and are pelagic, probably drifting with the plankton for quite a long time.