The mushroom creatures appear in "Memories of Boom Boom Mountain." They move by hopping on their stalk. They desperately want to dance, but there is no music. Their problem is resolved when the creatures hear jingles from the contraption Finn sets up to fan the flies away from the fish. When they start dancing in a patch of flowers, they knock some pollen loose, which in turn pollinates the mother Cactus Creature.
The mushroom creatures are grayish-brown and stand on one dark stalk. They mostly look like ordinary mushrooms; however, they appear to be mutated since other bodies are growing on their heads.