Acrosterigma magnum (Linnaeus, 1758) reaches about 50 mm (about 2 inches). This is one of the largest and more impressive species of the cockle family Cardiidae found in the western central Atlantic. The species is found in Florida, the Florida Keys, the Caribbean, northern South America, and in parts of the Gulf of Mexico (but not on the beaches of Southwest Florida.) The Magnum Prickly Cockle is notable for the delicate hues and smooth surface on the sculpture of radial ribs. (A large reproduction of this illustration is on display in the In Focus exhibition at the National Shell Museum.)
