Cap 10-15 mm across, at first conical, becoming convex to plano-convex with a prominent, acute papilla, hygrophanous, dark grey-brown to blackish when moist, sometimes paler at the margin, then cinereous to sepia-grey when drying, with black papilla, glabrous, translucent-striate, somewhat shiny and cartilaginous, margin sometimes crenulate with age. Gills (15-) 18-25 (-28) reaching the stem, ascending, broadly adnate, never decurrent, whitish to pale grey, the edge concolorous. Stem 20-50 x 1-3 mm, cartilaginous, cylindrical to compressed, glabrous, shiny, whitish to grey-ochraceous, sometimes dark grey or pale brownish towards the base, more or less rooting (up to 2.5 cm under the ground), the base covered with numerous, long, white fibrils. Odour absent. Basidia (20-) 25-40 x 5.5-9 µm, clavate, generally 4-spored, sometimes 2-spored or 1.spored at the same lamella, rarely 2-spored, with sterigmata up to 6 µm long. Spores 8-11(-13) x 6-8(-9) µm, Q=1.5-1.9, Qav=1.7, broadly pip-shaped, non-amyloid. Cheilocystidia 21-49 x 2.5-7.5 µm, occuring mixed with basidia, but partly forming a sterile band, variable in shape, cylindrical to clavate, never ventricose, often flexuous, smooth, apically obtuse, sometimes furcate or covered with a few short excrescences. Pleurocystidia absent. Lamellar trama non-dextrinoid. Hyphae of the pileipellis 2-4.5 µm wide, irregularly covered with sparse, obtuse, single or rarely furcate or branched, sometimes curved excrescences 1-10 x 0.5-2.5 µm. Hyphae of the cortical layer of the stem 1-4 µm wide, smooth, terminal cells 1-4 µm wide, often in clusters, irregularly clavate, flexuous, sometimes branched apically. Clamps present in 4-spored form, but not numerous, hard to find.
Ecology and distribution
Terrestrial, among mosses, wooden chips or humus, possibly preferring calcareous soil, and possibly also sometimes connected to buried wood. Summer to autumn. Very rare. Known from France, Switzerland, Spain, Germany and Norway.