Ascomata: 350-500 µm diam, scattered or aggregated in small clusters, pyriform, superficial or semi-erumpent, the neck papillate to truncate, 200-350 µm in height, periphysate; black, membranous, the upper part covered in short dark thick-walled obtuse agglutinated hairs 10-30 µm in length, mixed with dark brown flexuous hyphal hairs which extend over the whole of the exposed part of the ascoma. Peridium composed of three layers; the outer layer of mid brown angular cells to 13 µm diam, merging into an inner layer of hyaline compressed tissue. Interascal tissue composed of copious filiform paraphyses, swollen between the septa, without an obvious mucous coating. Asci 250-290 x 15-18 µm, narrowly clavate, rather long-stalked, thin-walled at all stages, the apex rounded to truncate with a conspicuous J- apical ring to 3.5 µm diam and ca 1 µm thick, 8-spored. Ascospores arranged bi- or triseriately, at first 52-68(-75) x 4-5 µm, often slightly sigmoid or weakly geniculate near the base, hyaline, thin-walled, aseptate and with two polar tapering gelatinous appendages 36-50 x 2-3 µm in size; eventually (often after leaving the ascus) becoming septate about at the upper third, the upper cell 15-21(-25) x 9-11 µm, becoming ellipsoidal to fusiform-ellipsoidal and dark brown, with a subapical germ pore.
Anamorph: Phialophora sp. fide Udagawa & Muroi (1979). Conidiomata absent. Conidiophores usually absent; when present visible only as short hyphal extensions to the conidiogenous cell. Conidiogenous cells 8-22 x 2.5-4 µm, solitary, ± cylindrical but gradually tapering towards the apex, pale olivaceous, proliferating percurrently with an obconical collarette 1.5-2 µm diam, periclinal thickening inconspicuous. Conidia 1.5-2 µm diam, ± globose to lacrymiform, hyaline, aseptate, thin- and smooth-walled, aggregated in slimy masses.
A common species, which has been confused in the past with Cercophora coprophila. That species has a tomentose ascoma, in contrast to the fruit bodies with agglutinated hairs seen in C. mirabilis. The description is taken from Lundqvist (1972) and Udagawa & Muroi (1979).