Invisighoul

The Invisighouls are, you guessed it, invisible ghouls! They only appear (or, er, 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 you can easily gobble up the furniture they throw at you and convert it into ammo that you can use to defeat Hector.