It can be found along the Atlantic coast of North America, ranging from North Carolina to the West Indies, Brazil, and Bermuda.

The valves have a roughly rectangular shape with a rounded anterior end and a slightly pointed posterior end.

They are usually purplish-white in colour, but live specimens are covered in a thin brown protective periostracum.

There are some distinct ribs on the posterior end and the margin is smooth.

The hinge is long and straight with a number of fine teeth.