Digga-Leg

Digg-Legg is a robotic boss appearing in the game Super Mario Galaxy 2. It resembles a smaller Megaleg with its weak spot being on its underside, containing a Power Star. However, it only has two legs and its eyes emanate a red glow. The only way to defeat it is for Mario to drill through the planetoid and strike its underside.

Trivia
The original robot had the case with the Power Star on top of it's head but this one has one on the bottom of it's head.