Mycena luxaeterna, common name eternal light mushroom, is a species of fungus in the Mycenaceae family. The mushrooms have parachute-shaped caps which start off darkly grayish-brown, changing to grayish-yellow or pale grayish-brown with a pale white ring at the edge when mature, and reach up to 2 cm (0.79 in) in diameter. Their thin, cylindrical, hollow, fragile stems up to 8 mm (0.31 in) in diameter are covered in a thick gel and emit a constant yellow-green bioluminescence (the caps do not glow). The gills are attached. The mushroom has a slightly radish-like smell and similar slightly bitter taste. It has been assigned the MycoBank number MB 515160.