Super Mario 3D World + Bowser's Fury has data for an unused Giga Mushroom, which resembles the Mega Mushroom but with a red-yellow color palette and an angry expression with a cross-popping vein, a common anime trope used for anger. It has seven animations, but each one contains no data. Touching it plays the "item into inventory" sound. If Mario touches it, he will become Mega Mario, and if Mega Mario touches it he will become Giga Cat Mario, suggesting it would have been used for Bowser's Fury.