Onix is a dual type Rock and Ground Pokemon introduced in Generation I. It evolves into Steelix when traded holding a Metal Coat. Take a look below for 26 fun and interesting facts about Onix.

1. Onix is a Pokemon composed of a giant chain of gray boulders that become smaller towards the tail.

2. Its length makes it the tallest Rock-type Pokémon.

3. It has black eyes and a rounded snout.

4. On top of its head is a rocky spine.

5. As it grows older, it becomes more rounded and smoother, eventually becoming similar to black diamonds.

6. Inside its brain is a magnet that serves as an internal compass.

7. Onix tunnels under the ground at over 50 miles (80 kilometers) per hour, which causes tremors and a terrifying roar that echoes a long way.

8. Hard objects encountered while tunneling are absorbed into its body, which makes it very sturdy.

9. It also consumes the boulders for food.

10. The massive, winding tunnels it leaves behind are used as homes by Diglett. 

11. As seen in the Pokémon Stadium series, Onix is capable of rotating its head, or any part of its body, in a full 360 degrees.

12. It is a very aggressive Pokémon that will constantly attack humans and other Pokémon when in pain, as seen in the anime. Onix can be found in mountains and caves.

13. Onix is the only unevolved Pokémon that is used in the Pokémon World Tournament by Trainers beyond the right attendant, being used in all of Brock’s teams.

14. The Onix line is the only one which can be completely acquired with in-game trades. However, this is only possible in Pokémon HeartGold and SoulSilver, in which the player can trade Bellsprout for Onix in Violet City, and any Pokémon for Steelix in Olivine City.

15. The Lagging Tail held item resembles the end of Onix’s tail.

16. Onix has the highest Defense of all unevolved Pokémon.

17. Onix is the largest unevolved Pokémon.

18. Onix is most likely based on a combination of a snake and earthworm.

19. It may also been based on the wyrm, a type of dragon that has been presented as limbless and burrowing.

20. Onix is a corruption of onyx (a mineral).

21. Brock’s Onix debuted in Showdown in Pewter City. He used it in his journeys in Kanto and Johto before giving it to his little brother, Forrest, for him to train in A Family That Battles Together Stays Together!. At some point before Grating Spaces, it evolved into a Steelix.

22. Ash and his friends encountered a giant Onix in To Master the Onixpected. It was on a rampage until Bruno managed to pull a Sandslash out from two of its boulders. Bruno captured the Onix afterwards.

23. The Crystal Onix featured a special Onix whose body is made out of glass crystal. Ash and his friends helped a glass sculptor named Mateo search for it because Mateo believed it would help inspire him to be better at his craft.

24. Onix debuted in Pokémon – I Choose You!. It was the next Pokémon a Trainer chose after the opponent’s Gengar put their Nidorino to sleep.

25. An Onix appeared in Hello, Pummelo!, under the ownership of Drake. He used it in the second round in the Orange League championship match against Ash; it battled Squirtle and was defeated.

26. Multiple Onix appeared in Tunnel Vision, where they resided in the Onix Tunnel and attacked anyone who attempted to pass through it. They were temporarily put to sleep by Jigglypuff‘s singing, but were eventually awakened by Team Rocket.