Digitate Thorny Oyster

Shell size to 65 mm; shell ovoid, scallop-like, with lower valve cemented to hard substrates. Upper valve with background sculpture of irregular radial cords crossed by concentric raised lines. Spines with flat, "duck-feet" extremities present on well-preserved or juvenile upper valves, but worn in beached ones. Color brick- to orange-red. Spondylus ictericus is a synonym.