Grumblump

Grumblumps are large, multicolored crystal blocks that appear in Super Mario 3D World, in the level "Grumblump Inferno". They behave similar to Tox Boxes and move along a set path on lava. As such, they are used to travel across the lava and progress through the level. Grumblumps can be cubed or rectangular.

Grumblumps have a smiling face on each side, which strongly resembles that of a Rhomp from Super Mario Galaxy 2. Once the player steps on a Grumblump, however, the smiling faces turn into frowning faces, and it starts rolling. As it moves, the player must stay on top of the block to avoid falling into the lava until it reaches the end of its path. A Grumblump may also encounter a slope along the way. If a player Ground Pounds on a Grumblump, the faces will turn angry, and the Grumblump will move faster for a short period of time. Occasionally, two Skipsqueaks may appear alongside the player to serve as guides for timing movements when trying to stay on top of the Grumblump.