Spirit Ball

Spirit Balls coming out of a translucent door.

Spirit Balls are strange ball-like ghosts that appear in Luigi's Mansion: Dark Moon. During his adventure to piece together the Dark Moon, Luigi comes across some places that have invisible objects. In order to reveal them, Luigi must use his Dark Light. When the light hits the invisible object, Spirit Balls come out. Luigi must use his Poltergust 5000 to suck them up in order for the invisible object to fully revealed. If he doesn't suck the Spirit Balls in a certain amount of time, they go back to the object and turn it invisible again.