Gold Chomp

The Golden Chomp is a special Incoming Chomp in Super Mario Galaxy. It appears in the Gusty Garden Galaxy, where it plays a prominent role in a hidden star mission in The Gusty Garden's Gravity Scramble. It contained a Power Star inside of it, but Mario could not break it open without help from a Rainbow Star - he obtained one after collecting a series of ? Coins.

Once he reached the Golden Chomp, he smashed it open, revealing the Power Star. Mario nabbed it, thus ending the mission.