Nestled within coral on hard reef, valves typically 1/3 exposed with closely-spaced external ribs visible.  Color pattern variable, with neat row of black eye spots along mantle margin and scattered papillae.  The incurrent siphonal opening is lined by simple or singly branched frills.  Attains 16 inches, but 10 inches is typical.  Red Sea to Okinawa and French Polynesia, excluding Hawaii.