Home > Invertebrates > Bivalves > Hyotissa numisma

Updated 8/20/2025

Family Gryphaeidae

INDO-PACIFIC / HAWAII

Hyotissa numisma

Portlock, Oahu, 35 feet

 

Makapu'u, Oahu, 20 feet

 


Sand Island, Oahu, 10 feet
   

COIN OYSTER

Common on the underside of ledges and under rocks in shallow water.  Attains 2 inches, 50 mm.  Red Sea to Hawaii and the Tuamotus.  Ostrea thaanumi, Ostrea hanleyana and Parahyotissa numisma are synonyms.