Clamperl is an aquatic Pokémon that makes its home on the seafloor. Its bivalve shell is dark blue with a silver rim along the inner edges. The shell is used to clamp down on prey, as well as for protection. A fully-grown shell will have nicks and scratches all over. Inside of the shell is a fragile, light blue body composed of six spherical extensions with a pink, pearl-like head in the center, usually depicted with its eyes closed. There is a circular white patch on each cheek.
The pearls produced by this Pokémon amplify psychic power and can be blue in color as seen in the anime. These pearls are also 10 times more valuable than pearls produced by Shellder. It is carnivorous, clamping down on prey without letting go until it stops moving. When it is close to evolution, Clamperl will become too big to fit inside its shell. Clamperl is the only Pokémon that gains extra effects by holding a Deep Sea Tooth or Deep Sea Scale.
It makes a single pearl during its lifetime. The pearl is said to amplify psychic power.