Skuller

Skullers are floating skull from Kirby's Dream Land. According to the game, they have small eyeballs. They replace Mumbies in the Extra mode. Just like Mumbies they can't be inhaled but they are much faster meaning Kirby will have a hard time avoiding them. When the Skullers move around the screen, their eyes and mouths open and close.

Trivia

 * Both Skuller and Mumbies are like Boos from the Mario series, though Mumbies don't always chase Kirby.