Mushroom Thriller is one of the Boss Pirates, the leaders of the Tabemon Monsters from the video-game "The Munchables".
He appears as a very large, very strange mushroom-like monster and attacks the Great Elder and the hero for trespassing on his new territory in a seemingly haunted house.
Mushroom Thriller attacks via firing spiked-wheels at the hero and powerful shockwaves, his weak-points are the smaller mushrooms on his head and after a battle he shares the same fate as the rest of the Tabemon Monsters and is devoured by the hero.