Cloyster is a black, pearl-like Pokémon. It is encased inside a light grey shell, which is surrounded by a second jagged, blue-violet outer shell casing. It has one barb-like spike protruding from above its head, and multiple conical horns on its outer shell. Its shell is harder than diamond with spikes that are even harder; harsh tidal currents will affect the size and sharpness of these spikes. On its pearl-like face, it has two white eyes and a mouth. Aside from its face and head, its internal anatomy has never been seen. Once it has shut itself in, it is impossible to open its shell from the outside. This impressive defense allows it to withstand anything from a bomb blast to even a missile strike. It lives on the sea floor, nestled among the rocks and coral.