Ubb is a playable character found in dark level 11, just before you encounter the enemy that chases you. Note: You can see his eyes glow in the lower half of the screen. Also, you must be in a local game to controll Ubb. Keep him alive until the middle of level 12, where a group of fins can be found. Ibb and Obb can die, but Ubb will remain alive and will stay on his spot.