Stone wheel

Stone Wheels are objects in Super Mario Galaxy. They are very common throughout the game, and are destroyed by Ground Pounding on them, usually leaving an item. Most of the time, the items inside are Star Bits. Like many other objects that can be manipulated with a Ground Pound, it has the Ground Pound symbol on it. It is noticeably cracked, and after being destroyed, the rock still leaves smaller pieces on the ground, which serve no purpose. Stone Wheels are also known from preventing Sproutles from growing, as a Bee states In the Honeyhive Galaxy. They can also sometimes appear in stacks. According to another Bee in the Honeyhive Galaxy, these stones can fall from the sky, similar to a Meteor.

Stone Wheels are important in the Toy Time Galaxy, since destroying a stack of Stone Wheels on Mecha Bowser's head causes the robot to explode, freeing the Gearmos trapped inside it.