Omnite

Omanyte is a small extinct cephalopod mollusk Pokémon similar to an ammonite or nautilus. It has a sky blue body with ten tentacles and a pale yellow, helix-spiraled shell on its back. The shell's rim has two circular indents where Omanyte's large saucer-like eyes protrude. If attacked or threatened, it quickly withdraws into its hard shell.

Omanyte is considered extinct, although it can be revived from Fossils. Its fossils have been excavated in areas that were once oceans long ago. Omanyte regulated its buoyancy by storing and releasing air within its shell and controlled direction by twisting its tentacles. While Omanyte fed on plankton, it was preyed on by Archeops and Carracosta. Omanyte can now be found in the wild due to being released by people or escaping after being restored to life, causing this species to become a problem.

Evolution
Omanyte evolves into .

(Source: Bulbapedia)