Onix (Japanese: イワーク Iwark) is a dual-type Rock/Ground Pokémon. It evolves into Steelix when traded holding a Metal Coat.
Onix resembles a giant chain of gray boulders, with a rocky spine on its head. This Pokémon has a magnet in its brain that serves as an internal compass. Onix's body becomes more rounded and smoother as it grows with age. A fully-grown Onix measures at an enormous 28 feet 10 inches, or 8.8 meters.