From Bulbapedia, the community-driven Pokémon encyclopedia.
The Skull Fossil (Japanese: ずがいのカセキ Skull Fossil) is a Fossil introduced in Generation IV that can be regenerated into Cranidos. It is the counterpart of the Armor Fossil.
In the core series games
If brought to the one of the following locations, the Skull Fossil can be regenerated into a Cranidos.
In the anime
A Skull Fossil was first seen excavated from the Oreburgh Mine in Shapes of Things to Come!. Roark was very interested in it, talking to it and telling it that it would come back to life. He then sent it off to the Oreburgh Mining Museum.
Kiawe found a Skull Fossil in Treasure Hunt, Akala Style!, during the Stoutland Search treasure hunt set up for Ash and his classmates by Olivia. A Skull Fossil also appeared on a holographic screen during Sophocles’s first hunt for treasure.
In the TCG
The following is a list of cards named Skull Fossil.