Length 40 mm, height 40 mm, breadth 35 mm. Shell solid, thick, quadrate in outline. Beaks strongly prosogyrated, adhere shells to which attached when juvenile. Lunule deeply impressed. Anterior margin strongly protruded, ventral margin straight meeting with straight posterior margin in right angle. Postero-dorsal margin slightly convex external ligament. Surface pinkish to yellowish orange in color, with 16─35 spiny radial ribs. Spines in anterior and central portions remarkably longer than the others. Inter-rib grooves granulous with small pits presenting a rough surface. Interior pale yellow to white. Cardinal armature strong. Right valve with prominent teeth while left with deep socket and postero-lateral tooth. Ventral margin finely crenulated.