The fungus produces a unique chemical compound, plectasin, that has attracted research interest for its ability to inhibit the growth of the common human pathogenic bacterium Streptococcus pneumoniae.

[4] The species was ulteriorly placed in Crouania by Friedrich August Hazslinszky von Hazslin, and in Plectania by Petter Karsten (1885), but neither placement is considered correct.

[6] The fruit bodies (technically called apothecia) typically grow in groups, or sometimes crowded closely together, with small stems or missing them entirely.

The inner surface of the cups bear the reproductive spore-bearing layer, or hymenium; it is brownish-black, with an edge that is often wavy and curved slightly inwards, and covered with fine hairs.

[10] The paraphyses (sterile filamentous hyphae in the hymenium) are enlarged at their tips and filled with brown colored matter, about 4 μm thick.

[8] Pseudoplectania sphagnophila resembles P. nigrella, but has a more deeply and persistently cup-shaped fruit body, a short but distinct stem, and only grows amongst sphagnum moss.

[13] P. nigrella has a worldwide distribution, and has been found in North America, the Caribbean,[14] Europe, India, Madagascar, New Zealand,[7] Israel,[15] and Japan.

[19] In laboratory tests, plectasin was especially active in inhibiting the growth of the common human pathogen Streptococcus pneumoniae, including strains resistant to conventional antibiotics.