From the Super Mario Wiki
Piro Dangles are enemies from Super Mario World 2: Yoshi's Island, its remake Yoshi's Island: Super Mario Advance 3 and Yoshi's New Island. They are invincible wisps of fire, with faces similar to that of Fryguy.
In the first game, Piro Dangles can only be found in a secret room in Burt The Bashful's Fort. These fire creatures simply travel around large blocks, and will hurt Yellow Yoshi if he touches one of them, similar to the Spark from Super Mario Bros. 2. In Super Mario Advance 3: Yoshi's Island, they reappear in Endless World of Yoshis, and can now be obliterated with a Special Blue Watermelon.
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