Circular to quadrangular, with subequal auricles, compressed, thin-walled, tan to brownish with mottlings or radial rays of purplish brown or black, with radial rays of overlapping flat scales or spines; interior nacre thick and yellowish, non-nacreous border with alternating light and dark bars. North Carolina to Florida, Bermuda, Bahamas, West Indies, Gulf of Mexico, Caribbean Central America, South America (to Brazil). Length 60 mm. Formerly known as radiata Leach, 1814 (Persian Gulf, Arabian Gulf, Mediterranean Sea).