Mollusks:
* Bivalves: These have two hinged shells.
* Clams: Common examples include littleneck clams, steamer clams, and razor clams.
* Oysters: Known for their pearl production and prized for their flavor.
* Mussels: Commonly found attached to rocks and other surfaces.
* Scallops: Recognized for their distinct, fan-shaped shells.
* Gastropods: These have a single, spiral shell.
* Snails: Common in both terrestrial and marine environments.
* Conchs: Large, colorful shells.
* Abalone: Found in the Pacific Ocean, prized for their pearly shells and edible meat.
* Cephalopods: These have an internal shell or no shell at all.
* Squid: Have a small, internal shell.
* Cuttlefish: Have a unique, porous internal shell.
* Octopus: Lack a shell entirely.
Crustaceans:
* Crabs: Have a hard exoskeleton and pincers.
* Blue crabs: Popular for their meat.
* Dungeness crabs: Known for their sweet flavor.
* Lobsters: Large, decapod crustaceans with ten legs.
* American lobster: Found along the Atlantic coast.
* Spiny lobster: Found in tropical and subtropical waters.
* Shrimp: Small, decapod crustaceans with ten legs.
* Crayfish: Also known as crawfish, are freshwater crustaceans.
Other:
* Barnacles: Marine crustaceans that attach themselves to rocks and other surfaces.
It's important to note that the term "shellfish" can be ambiguous, as some people may consider only mollusks or only crustaceans as shellfish.