Rock Mario

Rock Mario is a form first seen in Super Mario Galaxy 2, first appearing in the Boulder Bowl Galaxy. Mario can turn into this form when he touches a Rock Mushroom. By shaking the Wii Remote, Mario will transform into a giant boulder. In this form, Mario can roll around and jump, damaging enemies and big red crystals with items inside them. If Mario touches certain enemies or a wall, he will revert to his rock form, but can be turned back into a giant boulder if the player shakes the Wii Remote. It is possible to turn back to normal by jumping and pressing Z. This is useful to stop Mario from flying off an edge; however, this move has been disabled during the second mission of Melty Monster Galaxy - it would make the mission far too easy.

The form later makes a small appearance in the Freezy Flake Galaxy where it was used to collect Launch Star pieces. The Melty Monster Galaxy, however, made extensive use of the power up in two of its missions. In the mission "The Chimp's Bowling Challenge", Mario had to use the Rock Mushroom to defeat Pinheads and score a total of 5000 or more points. In the galaxy's second mission, "A Stroll Down Rolling Lane", Rock Mario was needed to get across a large track to the Power Star.