The giant clam is the largest bivalve on Earth and a keystone reef inhabitant found throughout Indo-Pacific coral gardens. A massive shell can exceed 1 metre across, with a gaping opening lined in brilliant blues, greens, and purples. Unlike most clams, it hosts symbiotic algae in its tissues and feeds partly on sunlight; divers will find it anchored in shallow reef zones, often in the same spot for years. Despite its fearsome reputation in popular culture, it is not a threat to divers—the shell closes too slowly to trap anything larger than a finger.
Most likely to be seen at
Sites where its range and habitat make it likely — not yet confirmed by a logged sighting.