Speedy Spirit

Speedy Spirits are rare ghosts found in Luigi's Mansion.

Speedy Spirits are pale blue and have a similar build to a Gold Ghost. Unlike others who attack Luigi, Speedy Spirits hide from him. If they are discovered by examining an object, they panic and try to run off. Luigi must shine his Flashlight on it and immediately suck it up before they flee. If Luigi manages to capture one of them, it yields a large amount of treasure, which always includes Coins, but sometimes includes valuable treasures, such as Stones. In the PAL Hidden Mansion, all Speedy Spirits drop Silver Diamonds, but they do not drop any Stones. In the Nintendo 3DS version's Hidden Mansion, the Speedy Spirit locations are changed. There are a total of 15 Speedy Spirits in the mansion. Gold Mice are similar treasure-yielding Ghosts.

Speedy Spirits are only found when a room is dark. Luigi should search everything in a room carefully before turning on the lights. Also, the length of time they are stunned by the flashlight is the shortest of any ghost. If Luigi doesn't uncover a Speedy Spirit and the lights turn on in the room, they will be gone forever. Also, if Luigi uncovers a Speedy Spirit and fails to catch it, it never comes back, even during the blackout. However, some Speedy Spirit ghosts are only able to be captured during the blackout. Luigi can use an Elemental Ghost to defeat a Speedy Spirit, but the Speedy Spirit won't drop anything if he does.

A Speedy Spirit also appears in Mario & Luigi: Superstar Saga in Starbeans Cafe as a representative sent by Professor E. Gadd to taste a new drink.

They are the equivalent of a Gold Greenie from Luigi's Mansion: Dark Moon.

Hidden Mansion (Nintendo 3DS version)
Washroom 2F/ Inside the heater below the poster

Reference
Spirito riccone