Shellfish include mussels, cockles, periwinkles, clams, and oysters. Bivalves include clams, oysters, cockles, mussels, scallops, and numerous other families. Seafood includes an array of shellfish such as crabs, clams, cockles, crayfish, shrimp and squid. Butter clams, horse clams, and cockles were dried for trade. They are also fed mollusk such as sea snails, oysters, cockles etc.. This subclass includes the edible clams, the cockles and the Venus clams. Frozen and cut bait such as prawns, mussels, cockles and fish pieces are also effective. Snapper, flounder, mullet, scallops, cockles and pipi provided food in plentiful amounts. Wales is known for its shellfish, including cockles, limpet, mussels and periwinkles. Other Pleistocene invertebrates of California included hardshell cockles, spiny cockles, and oysters. Shellfish abundance has declined, especially toheroa, scallops, tuatua, cockles and pipi. These dues included oysters, mussels, cockles, rushes, and wine. Both the men and women go searching for cockles and mussels, which fetch better prices. Cuvier categorized snails, cockles, and cuttlefish into one category he called mollusks ("Mollusca"), an embranchment. Bates runs a shellfish company that harvests cockles mainly for the Spanish market.