[1] This species grows up to three inches in maximum width, and is similar in shape and sculpturing to the Atlantic bay scallop.

The shell of the Atlantic calico scallop has about 20 radial ribs, which are sometimes roughened by growth lines.

The exterior coloration of the upper (left) valve of this species is most typically a mottled pattern of purple on a cream background.

The lower (right) valve of this scallop is usually whitish with small reddish or purple spotting on the sides.

The other is the rough scallop, (Aequipecten muscosus), which has unequal 'ears' and has sharp scales on the lower surface of the ribs.