This looks like a tiny Puffstool without antennaes. It's slightly larger than a Dwarf Bulbear. It's one of the game's harmless enemies, and it just uproots itself when you walk nearby, then it runs away. Without eyes though, it's not the smartest little fungus. It might run into walls and topple over in a Puffstool-esque fashion! The reason it looks like a Puffstool is because it is an ancient type of skitterling that mutated over generations thanks to the prolonged exposure to air heavily laden with Puffstool spores.