Boo Blah

A Boo Blah is a kind of ghost that appears in Super Mario World 2: Yoshi's Island. This creature sticks to the ceiling or the floor and jumps up periodically. A large majority lives inside Bigger Boo's fort along with other spirits and Boos. They are invincible but are not a problem, as they only hurt the player if they somehow make contact with him or her while jumping up. Stomping them stuns them for a brief period of time They can be defeated by using a POW block or a cloud item.

Trivia

 * They could have been the inspiration for Luigi's Mansion ' s Ceiling Surprises, which are similar to them.
 * They look incredibly similar to the Camo Goblin enemy that appears in the DX version of The Legend of Zelda: Link's Awakening.