Live clams, oysters, mussels and scallops should have tightly closed shells and a mild odor. Shells should not be cracked, chipped or broken. If a shell is open, test to see if the shellfish is still alive by tapping on the shell. Live shellfish will close when tapped. Discard all shellfish that are not alive.
Clams range in color from pale to deep orange.
Oysters are typically creamy white but may also be tinted green, red, brown or pink. Mussels can be light tan to deep orange. Scallops should have a mild, sweet odor and look moist, but they should not be standing in liquid or in direct contact with ice. Live lobsters and crabs should have hard shells and be moving their legs. For food-safety reasons, lobsters must be cooked live or killed immediately before cooking.