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. 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.