Shell size to 180 mm; shell light, thin, elongate. Sculpture of concentric ridges and strong radial ribs. Scale-like projections form at intersections of ridges and ribs. Pair of spoon-shaped structures under umbones, called apophyses, are points of attachment of foot muscles. Color pure white, seldom with delicate pinkish internal coloration. Borer in mud bottoms in protected bays. After storms, loose valves wash on Gulf beaches near inlets.