Four postcard stamps celebrate the wonder of seashells. Each stamp depicts one iconic shell found in North American waters: the alphabet cone, the Pacific calico scallop, the zebra nerite, and the Queen conch, commonly known as the pink conch. The highly stylized stamp art expresses a lighthearted, artistic view of shells. The horizontal swaths of white and blue in the background suggest waves washing the shells onto a beach.

The Pacific calico scallop is also known as the Mexican Bay Scallop, Catarina Scallop and Speckled Scallop. Its shells vary from nearly all white to blotched and streaked with solid dark purple, orange, or brown.  Natural distribution of the Pacific calico scallop ranges from both sides of the Baja California Peninsula in Mexico to Peru. These scallops have been commercially harvested in Baja California since the 1970s, principally by divers collecting them by hand.