The two main types of fish are flat and round. Flat fish, such as flounder and halibut, have a flattened body shape with both eyes on one side of their head. Round fish, such as salmon and tuna, have a cylindrical body shape with eyes on opposite sides of their head. Univalve and bivalve refer to types of shellfish, such as snails and clams. Abalone and clam are specific types of shellfish. Cephalopod and crustaceans are other types of seafood, including squid and shrimp.