Scallops are part of the phylum Mollusca, a large group of animals that also includes snails, sea slugs, octopuses, squid, oysters, clams, and mussels. They have two hinged shells that are formed of calcium carbonate and up to 200 eyes lining their mantle. You can find them in saltwater environments worldwide. Large populations are found in the Sea of Japan, off the coast of Peru and Chile, and near Ireland and New Zealand.