Mycena stylobates, commonly known as the bulbous bonnet, is a species of inedible mushroom in the Mycenaceae family. Found in North America and Europe, it produces small whitish to gray fruit bodies with bell-shaped caps that are up to 15 mm (0.6 in) in diameter. The distinguishing characteristic of the mushroom is the fragile stem, which is seated on a flat disk marked with distinct grooves, and fringed with a row of bristles. The mushrooms grow in small troops on leaves and other debris of deciduous and coniferous trees. The mushroom's spores are white in deposit, smooth, and ellipsoid-shaped with dimensions of 6–10 by 3.5–4.5 μm. In the development of the fruit body, the preliminary stem and cap structures appear at the same time within the primordium, and hyphae originating from the stem form a cover over the developing structures. The mycelia of the mushroom is believed to have bioluminescent properties.