Handsome Fungus Beetle

It was a black bug with 4 yellow spots on it's back, around 1 cm in size. It was sitting on the underside of a big mushroom growing on a tree. It had small, thin stick-like legs and had a curvy shape, with two black antennae on it's head. The fungus beetle has a relationship with the fungi, because the fungi provides it a home and a source of energy. This relationship is commensalism, because the fungus beetle gains something, but the fungi doesn't gain or lose anything.