Gearmos are small robot allies to Mario that appear in the Super Mario Galaxy and Super Mario Galaxy 2 video games. In the original Galaxy most of them live in Toy Time Galaxy, but some can be found in Buoy Base Galaxy, Battlerock Galaxy and Dreadnought Galaxy.
In Super Mario Galaxy 2, two Gearmos, a gold and a silver one, can be found in Boulder Bowl Galaxy and Space Storm Galaxy, respectively. The Gold one says he wants a Goomba and the Silver one says he wants a Topman. If Mario completes one of those missions, the Gearmo will give Mario a Power Star.
If Mario gets zero purple coins in Battlerock Galaxy, the Gearmo at the end will reference to himself as "this old iron lady".