Oysters: Family Ostreidae
True oysters (Pearl oysters are another family) have central abductors like scallops and some of the important shgells in my collection are oysters or relted to oysters. The "duck foot" shells which resemble duck's feet are oyster shells. The are usually dark and sometimes white or light color. The "Kitten's paw" shells, though not related, closely resemble some of the thin Eastern oyster shells.
Some of the smaller Eastern oyster shells resemble the fingers of hands.