The world’s biggest bivalves are the aptly named giant clams. Inhabiting the warm waters of the Indo-Pacific, the largest of these species, the eponymous giant clam (Tridacna squamosal), can reach up to 1.2 meters (4 feet) in length and wiegh over 230 kilograms (500 pounds). Historically known as the killer clam for its supposed ability to trap careless divers, these harmless and colorful bivalves are favorite animals for divers and snorkelers to spot, but they may also be big players in the ecosystem.