Crustacean or mollusk? Can you tell the difference?

You probably know how to distinguish a mussel from a barnacle, but do you know which is a crustacean and which is a mollusk?.

Crustaceans (from the Latin crusta, “crust, bark”) have a hard or flexible shell and can be of two types: elongated body (such as prawns, shrimp, shrimp, lobster, crayfish or crayfish) and short body (such as spider crab, crab, velvet crab or barnacle).

The molluscs (from the Latin molluscus, "soft"), have a soft body that may be covered by a single shell (univalves or gastropods), by two shells (bivalves), or naked and with tentacles (cephalopods). Among the univalve mollusks (with a single shell) are the limpet, the periwinkle, and the clam. Among the bivalve mollusks (with two shells), we find mussels, razor clams, scallops, cockles, scallops, cockles, and oysters. Finally, among the cephalopods, there are the squid, cuttlefish, and clams. octopus and the squid.