In the Bonin Islands it is called "Green Pepe". The cap is initially convex before flattening out (sometimes forming a central depression), and measures up to in diameter. The cap has radial grooves extending to nearly the center, and sometimes develops cracks in the margin, which has small rounded teeth. Its color is pale brownish gray that fades after expansion, and it is somewhat sticky. The white stem is long by 0.3–1 mm thick, hollow, and translucent. It has tiny hairs on the surface. The base of the stem is disc-shaped or somewhat bulbous, measuring 1–2.5 mm wide. The thin gills are free from attachment to the stem, or are adnexed (narrowly attached) to a slight collar encircling the stem. Initially white then grayish in color, they are somewhat crowded, with 17–32 full-length gills and 1 to 3 tiers of lamellulae (shorter gills that do not extend fully from the cap margin to the stem). The gills are 0.3–1 mm wide with micaceous edges. The flesh is very thin, and has a strong odor of ammonia. Both the caps and the gills are bioluminescent, while the mycelia and stems have little to no luminescence. The spores are white, smooth, roughly elliptical, and have dimensions of 7–8.5 by 5–6 μm. The basidia (spore-bearing cells) are 17–23 by 7.5–10 μm, and four-spored with sterigmata around 3 μm long. The paraphyses are 5–8 μm wide, shorter than the basidia, more abundant and form a somewhat gelatinous layer. The cheilocystidia (cystidia on the cap edge) are 60 by 7–21 μm, hyaline, conical or ventricose (inflated). The tips of the cheilocystidia are drawn out to a point, or have a short appendage measuring 15 by 2–3 μm, which is sometimes branched, and is thin or slightly thick-walled. There are no cystidia on the gill face (pleurocystidia). Pileocystidia (cystidia on the surface of the cap) are club-shaped, measuring 25–60 by 13–25 μm. They are somewhat thick-walled, and spiny on the exposed surface with short simple outgrowths extending up to 3 μm long.