Crux

Crux, "The Southern Cross" is one of the Silver Key Celestial Spirits that is owned by Lucy Heartfilia. It is unknown if Crux can be used for combat purposes. However, it is known that Crux has the ability to search for information about Celestial Spirits and their owners by sleeping, though he's forbidden to reveal too much, as one's activities are still a private matter in the Spirit World. His full name is Crumudgeon.