The shell is small, thick and very inequilateral as well as compressed laterally. Umbones are small and situated behind the midline. The outer surface is rather smooth with fine concentric lines , becoming strong and rugose on the posterior slope. The periostracum is thin and glossy. The hinge of the right valve has one anterior and two posterior lateral teeth, against one anterior and one posterior lateral teeth in the left valve. The pallial sinus is deep and broad. The internal margins are smooth. The color of the shell can vary, but is often white, cream, brown, gray, or purple; it often has ribs, and the ventral side has darker radiating bands.