Mikaruge

Mikaruge is a ghostly purple Pokémon attached to a stone. Although lacking a physical body, Mikaruge projects its appearance out of a small rock called the Odd Keystone. The rock is trapezoidal in shape and has two small dots. There is a crack running down the middle, splitting in two near the bottom. The crack in combination with the two dots appears to form a frowning face. Mikaruge's projected appearance is an ethereal composition of swirling purple fog. Its face is set in the middle of the fog and contains green, crescent eyes that are connected to its jagged mouth. Its pupils are composed of a spiral and it is sometimes only seen with one. Swirling around its face are green orbs with yellow centers.

Mikaruge is formed by the collection of 108 spirits being trapped in an Odd Keystone by a traveler due to misdeeds it caused. Some of the spirits mixed in Mikaruge are ill-natured. Some Mikaruge are up to 500 years old.

(Source: Bulbapedia)