Boo Man Bluff
From the Super Mario Wiki
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A Boo Man Bluff is a species of Boo, encountered only in Super Mario World 2: Yoshi's Island, its remake, and Super Princess Peach. It is an orange Boo with a black bandanna tied over its eyes. Since it cannot see, the Boo relies on sound to guide it. When it hears a sound, such as a Yoshi gathering coins, it will home in on the sound.
In Super Princess Peach, they only come in huge swarms. If Peach is hit by the swarm, she will have to go back to the start of the room she is in. The chase ends when the princess leads them into light, defeating them. In Bowser's Villa, they are very fast, and can only be outran through use of the Gloom vibe.
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