It appears to be based on a bivalve of the genus Spondylus with a black pearl as its head.
Cloyster may be a combination of clam and oyster. It may also be a play on cloister (to seclude or shelter oneself).
Parshen may be a combination of パール pearl and シェル shell.
No: 091
English Name: Cloyster
Japanese Name: Parushen
Generation: 1
Type: Water, Ice
Species: Bivalve Pokémon
Abilities: Shell Armor, Skill Link, Overcoat (hidden ability)
Evolution: Shellder > Cloyster
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.
It typically only opens its shell to attack an opponent. However, it is fully capable of retaliating against any enemy with its shell tightly closed. With rapid succession, it launches its spikes at the foe, keeping them repelled. 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. The same projectile system it uses to launch its spikes is also used for swimming. It swallows seawater, and then ejects it towards the rear propelling it through with siphon-jet propulsion. It lives on the sea floor, nestled among the rocks and coral.
POKEDEX ENTRIES
Pokemon Red: When attacked, it launches its horns in quick volleys. Its innards have never been seen.
Pokemon Blue: When attacked, it launches its horns in quick volleys. Its innards have never been seen.
Pokemon Yellow: For protection, it uses its harder-than-diamonds shell. It also shoots spikes from the shell.
Pokemon Stadium: Its shell is so hard, it can even withstand a bomb. No one has ever seen what is inside its shell.
Pokemon Gold: Once it slams its shell shut, it is impossible to open, even by those with superior strength.
Pokemon Silver: Cloyster that live in seas with harsh tidal currents grow large, sharp spikes on their shells.
Pokemon Crystal: Even a missile can’t break the spikes it uses to stab opponents. They’re even harder than its shell.
Pokemon Stadium 2: Once it slams its shell shut, it is impossible to open, even by those with superior strength.
Pokemon Ruby: Cloyster is capable of swimming in the sea. It does so by swallowing water, then jetting it out toward the rear. This Pokémon shoots spikes from its shell using the same system.
Pokemon Sapphire: Cloyster is capable of swimming in the sea. It does so by swallowing water, then jetting it out toward the rear. This Pokémon shoots spikes from its shell using the same system.
Pokemon Emerald: It swims in the sea by swallowing water, then jetting it out toward the rear. The Cloyster shoots spikes from its shell using the same system.
Pokemon FireRed: Its shell is extremely hard. It cannot be shattered, even with a bomb. The shell opens only when it is attacking.
Pokemon LeafGreen: When attacked, it launches its horns in quick volleys. Its innards have never been seen.
Pokemon Diamond: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
Pokemon Pearl: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
Pokemon Platinum: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
Pokemon HeartGold: Once it slams its shell shut, it is impossible to open, even by those with superior strength.
Pokemon SoulSilver: Cloyster that live in seas with harsh tidal currents grow large, sharp spikes on their shells.
Pokemon Black: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
Pokemon White: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
Pokemon Black 2: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
pokemon White 2: It fights by keeping its shell tightly shut for protection and by shooting spikes to repel foes.
Pokemon X: Cloyster that live in seas with harsh tidal currents grow large, sharp spikes on their shells.
Pokemon Y: Its shell is extremely hard. It cannot be shattered, even with a bomb. The shell opens only when it is attacking.
Pokemon Omega Ruby: Cloyster is capable of swimming in the sea. It does so by swallowing water, then jetting it out toward the rear. This Pokémon shoots spikes from its shell using the same system.
Pokemon Alpha Sapphire: Cloyster is capable of swimming in the sea. It does so by swallowing water, then jetting it out toward the rear. This Pokémon shoots spikes from its shell using the same system.
Pokemon SUN: Its hard shell cannot be shattered—not even by a bomb. The contents of the shell remain unknown.
Pokemon MOON: Excavation of the tombs of ancient hunting tribes has turned up many spears tipped with spikes that had fallen off this Pokémon’s shell.
