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Grates are disc-shaped objects appearing in Super Mario Galaxy 2. They are featured during Flip-Flopping in Flipsville, a mission in Flipsville Galaxy, where they grant a connection between two different surfaces of a platform. Ground Pounding on a Grate causes Mario to flip to the other side of the planet, changing gravitation and allowing him to walk on that side. Simply falling off the platform does not switch the force of gravitation.
Grates are also helpful in defeating certain enemies. Pounding a Grate while a Pupdozer walks over it is the only way to defeat the enemy. Moreover, Grates play a major role in the battle with Glamdozer, where the player needs use them and slam the boss from underneath four times in order to defeat her. However, during battle, Glamdozer often shoots large blobs of lava that can fill in the Grates temporarily, rendering them unusable during that period of time.