Summary:
Features include 1) resupinate growth (rarely bent outward to form a narrow cap) on wood and bark, but also leaves, needles, and soil, 2) color that is orange predominantly, 3) a merulioid surface with broad ridges, 4) a margin that is firmly attached, matted-tomentose, with white to orange, scattered hyphal strands, 5) spores that are broadly elliptic, smooth, dextrinoid, pale yellow to almost colorless, and cyanophilic, 6) cystidioles that are common, projecting, 2 microns wide, and clavate or with a finger-like projection at the apex, 7) a monomitic hyphal system: generative hyphae with clamp connections, some encrusted with crystals.

Microscopic:
SPORES 5.6-7.2(7.6) x (3.8)4-4.8(5.2) microns, broadly elliptic or occasionally slightly oboval, adaxially flattened, with a distinct broad, blunt apiculus, smooth, dextrinoid (but the reaction sometimes weak), pale yellow to almost colorless, cyanophilic, wall about 0.3 microns thick; BASIDIA 4-spored, (20)25-35(45) x (6.5)7-9(10) microns, clavate, sterigmata 4.4 microns long; CYSTIDIOLES common, projecting up to 40 microns, "clavate, in some specimens with the apex elongated" and finger-like; HYPHAE monomitic, generative hyphae, of context (2.5)4-7.5(9) microns wide, woven, distinct, colorless, thin-walled, with clamp connections, some hyphae "with segments heavily crystalline or granule incrusted"; "tramal hyphae in some specimens embedded in gelatinous matrix"; hyphal strands "scattered to numerous, when narrow (-15 microns) composed of hyphae of the same diameter, when broad they are composed of one or a few broad core hyphae which are protected and bound together by narrower hyphae", (Ginns(15)), SPORES 4.5-5.5 x 3-3.5 microns, elliptic, dextrinoid, cyanophilic, thick-walled; BASIDIA 4-spored, 15-25 x 4-5 microns, clavate, with basal clamp connection; CYSTIDIA none; HYPHAE monomitic, hyphae thin-walled, with clamp connections, in the subhymenium 2-3 microns wide, richly branched, in the subiculum 3-8 microns wide, straighter and sparsely branched, "as a rule with attached doublepyramidic crystals", (Eriksson)

Notes:
Leucogyrophana mollusca has been found in BC, WA, OR, ID, AB, NS, NT, ON, PQ, AK, AL, AZ, CA, CO, IN, MA, ME, MI, MT, NH, NM, NY, PA, TN, and VT, (Ginns(5)). It occurs in Scandinavia including specifically Sweden, (Eriksson).