Omanyte and Omastar, Kabuto and Kabutops. It is believed these Pokémon became extinct tens of thousands of years ago. The details of their behavior are shrouded in mystery. Though some have speculated that they may still exist, none of these Pokémon have ever been seen alive.
Omanyte, the Spiral Pokémon. Believed to have lived over 2 billion years ago. Recent research indicates that it was able to control its buoyancy by storing and releasing air in its shell.