The complete Pokemon RBY pokedex, part 13

Pokémon Name: Omanyte
Type: Rock/Water
Classification: Spiral Pokemon
Pokédex Number: 138
Ability: Swift Swim
Dream World ability: Weak Armor
Useful Attacks: AncientPower
Location Found:
D/P/P/HG/SS: Revive from Helix Fossil
B/W: Revive from Helix Fossil received from fossil man in Twist Mountain

One of a handful of extinct Pokemon that can live again thanks to intact fossils found throughout the game world.

Evolution: To Omastar at 40