There’s some easy signs to look for when cooking seafood: prawns, crab and lobster shells will turn pink in colour, with their meat turning white and becoming firm.
Live oysters, clams and mussels will have open shells once they are cooked. Scallops will also turn white when cooked and become firm.
If you are cooking live Oysters, clams or mussels, make sure you don’t put any already opened shells in before cooking and remove any that are still closed after cooking.