Spirit Ball

Spirit Balls are ghosts that appear in Luigi's Mansion: Dark Moon. Their appearance is based on the Will-o'-the-wisp. After Luigi uses the Dark-Light Device on an invisible object to reveal it, Spirit Balls fly out, where Luigi must use his Poltergust 5000 to suck them up in order for the invisible object to fully revealed. If he does not suck the Spirit Balls in a certain amount of time, they go back to the object and turn it invisible again. Spirit Balls can hurt Luigi if touches them, dealing five HP of damage.

In a mission in Gloomy Manor, it is seen that a Boo can produce some Spirit Balls. Unlike other ghosts, they cannot be sent to the Vault, nor do they appear in the ScareScraper; invisible objects simply get revealed without needing to suck them up.