Invisighoul

The Invisighouls are invisible ghosts. They only appear (or don't appear) during the boss battle with Hector the Reflector in Yoshi's Island DS. They sometimes throw chairs and flower pots at Yoshi during the battle. However, they're more of a help than a hinderance, as Yoshi can easily gobble up the furniture they throw at him and convert it into ammo that he can use to defeat Hector.