Cloyster has a large shell covered in spikes. Six of the spikes are long and conical, resembling turrets, and are used to protect its soft insides from foes. However, the shell offers a lack of protection against special attacks. Cloyster has an inner, gray-colored layer inside its purple shell. Its "head" and face resemble a black pearl, and there is a jutting, horn-like white spike above its "head". Its face is similar to Gastly, though the two Pokémon are not related.
Cloyster have strong defenses and moderate offenses, both thanks to their sturdy shell. They fight by clamping their shell tightly shut while launching spikes from their shell to strike opponents.
Cloyster are sneaky and clever Pokémon, viciously rushing at prey while shooting spikes. They fight roughly because of the hostile nature of their habitat and the protection of their shell, allowing them to withstand physical blows easily. Cloyster swim by means of propulsion, doing so by first swallowing water, and then jetting it out toward the rear. Cloyster may also shoot spikes from their shell using the same system.
Cloyster live deep under the sea, usually on the seabed or amongst coral and rocks. Their range is basically the same as Shellder's.
This Pokémon was unavailable prior to Generation I.