From the Super Mario Wiki
A Boo Balloon is a Boo in the shape of a blue balloon in Super Mario World 2: Yoshi's Island. They race about the screen, trying to deal damage to Yoshi. They will inflate when hit with a Yoshi Egg. After three hits, they will explode, yielding coins or sometimes a ! Switch.
Names in other languages
- ^ Super Mario World 2: Yoshi's Island Nintendo Player's Guide. Page 126.