Common Pearl Oyster

Found attached to coral and rock debris or lying freely, over dead coral, coarse gravel, sand and in seagrass beds of lagoon reefs.
Widespread Indo Pacific

These oysters are harvested for their pearls.

Most Bivalves are permanently anchored in fissures or depressions in the rock surface of the reef, some may become covered in algae and other marine life.
Other Bivalves swim free, either by a well developed foot or propelled along by a jet of water from their mantle cavity.