A stout, thick shelled species characterized by deep concentric grooves except on the early growth stage, a fine pustulose surface, and remnants of a thick periostracum in the grooves near the margin. Exterior whitish, interior with a purple tinge around the margins and at the hinge. Length, 60-90 mm.

Fairly common in coarse gravel near rocky areas along the exposed coast, from low tide to shallow sublittoral depths.

Santa Barbara, CA to Cape San Lucus, Baja CA.