Cloyster

Cloyster is a bivalve Pokémon, known for its incredibly hard shell that is said to be tougher than diamonds. Introduced in Generation I, it evolves from Shellder when exposed to a Water Stone. Its natural habitat is deep ocean waters, where it remains mostly stationary, waiting for prey. Cloyster's diet consists primarily of small fish and aquatic organisms, which it ambushes by opening its shell and then clamping down. In the Pokémon games and anime, Cloyster is often depicted as a powerful defensive Pokémon, capable of withstanding massive damage and retaliating with strong Water and Ice-type moves. Its spiky shell and intimidating appearance make it a memorable figure. Type matchups see it strong against Fire, Ground, and Rock types, but vulnerable to Electric and Grass attacks. Its unique ability to close its shell so tightly that it becomes invulnerable has contributed to its cultural significance as a symbol of impenetrable defense.