The Coral-eating Mussel
The Coral-eating Mussel, Gregariella coralliophaga (Gmelin, 1791), is a coral-rock boring species, found locally within small coral branches strewn on the beach after storms. The common name is a misnomer, as these mussels do not eat coral, only use the coral skeleton as a substrate for boring. The 20-mm (about ¾ inch) shell is inflated, with a strong ridge on its postero-dorsal part. The shell margins are finely serrated. The shell interior is iridescent, bluish-white. The periostracum is thick, heavy, but often absent in dead shells.
The Coral-eating Mussel, Gregariella coralliophaga, from Sanibel. Photos by José H. Leal.