|First appearance||Super Mario Galaxy (2007)|
|Latest appearance||Super Mario 3D All-Stars (2020)|
|Effect||Turns Mario into Boo Mario or Luigi into Boo Luigi|
- “What do we have here...? Looks like a soft, white mushroom, eh? You know, the stuff you're finding is pretty weird... But I guess that's just the universe we live in, right?”
- —Lubba, Super Mario Galaxy 2
The Boo Mushroom gives Mario the ability to float in midair and move through specific types of barriers by using the Spin command to become temporarily intangible. Negatively, Boo Mario attracts other Boos towards him, who can harm him and revert him back; exposing Mario to a light beam will also get rid of the power-up.
Super Mario Galaxy
The power-up is introduced in the mission Luigi and the Haunted Mansion in the Ghostly Galaxy, where Mario has to meet and free Luigi by breaking into his sealed room with the help of the Boo abilities, though Luigi is too scared of Mario in his Boo form, so the player has to use a nearby light to turn back to normal.
The Boo Mushroom reappears in the Sand Spiral Galaxy, where Mario has the choice of using either it or the Bee Mushroom to traverse the course. It is featured a last time in the Boo's Boneyard Galaxy, where Boo Mario must race the Spooky Speedster.
Super Mario Galaxy 2
Puzzle & Dragons: Super Mario Bros. Edition
Boo Mushrooms are Transformation items in Puzzle & Dragons: Super Mario Bros. Edition. They are used to transform allies such as Red Koopa Paratroopas into Dry Bones or Buzzy Beetles into Bony Beetles, and can be obtained from ? Blocks or dropped by Dark attribute enemies defeated with 10+ combos such as Big Boo, Boo Crew or Boo Trio.
Super Mario series
Super Mario Galaxy
- Trading card bio: "When traveling through the Ghostly Galaxy, Mario needs some extra help to navigate this scary place filled with Boos and Bouldergeists. A Boo Mushroom is just what he needs. When Mario grabs this white mushroom, he transforms into Boo Mario and is able to float, and pass through solid walls for a short time."
Super Mario 3D All-Stars
- North American website bio: "Float around as not-so-scary Boo Mario, passing through walls and other barriers—at least until he runs into light or water!"
The "Super Mario Power Up" series of keychains from Nintendo TOKYO
Names in other languages
|French||Champignon Boo||Boo Mushroom|
|Italian||Fungo spettro||Spectre/Ghost Mushroom|
|Portuguese||Cogumelo Bu||Boo Mushroom|
|Spanish||Champiñón fantasma||Ghost Mushroom|
- The card description for this item implies that there are multiple Bouldergeists in the level by using its name in a plural sense, although only one exists in the game.