Although it is primarily a saprotrophic species, feeding on the decomposing organic matter remaining after a fire, it also forms biotrophic associations with the roots of Norway spruce.

The fungus was first described scientifically from Europe in 1805 by Johannes Baptista von Albertini and Lewis David de Schweinitz as Peziza carbonaria.

[2] Mordecai Cubitt Cooke illustrated the fruitbodies, spores, and asci in his 1879 work Mycographia, seu Icones fungorum.

[6] In 1860 Miles Berkeley and Moses Ashley Curtis described the species Peziza lepida from collections made in Japan as part of the North Pacific Exploring and Surveying Expedition (1853–1856).

[12] The fruitbodies (ascocarps) of Geopyxis carbonaris are cup shaped, 5–20 millimetres (1⁄4–3⁄4 inch) wide,[13] and have fringed whitish margins.

The paraphyses are slightly club-shaped, unbranched, and have irregular orange-brown granules, with tips up to 5 μm wide, and are not forked or lobed.

[21] Other genera with similar species with which G. carbonaria may be confused include Aleuria, Anthracobia, Caloscypha, Melastiza, Pithya, and Sowerbyella.

[26] Other cup fungi often found fruiting in the same area as G. carbonaria include those from the genera Aleuria, Anthracobia, Peziza, and Tarzetta.

[27] Although primarily a saprotrophic fungus involved in the post-fire breakdown of duff and coniferous roots, Geopyxis carbonaria has been shown to be capable of forming ectomycorrhizae with Norway spruce (Picea abies).

[28][29] Additionally, the fungus produces the enzyme polyphenol oxidase, and can break down the complex organic polymer lignin—features characteristic of saprotrophic fungi.

[30] The formation of a rudimentary Hartig net, a characteristic of mycorrhizal fungi, indicated that G. carbonaria might be capable of forming mutualistic relationships under the right conditions.

Vrålstad and colleagues suggest that its below-ground association with spruce roots protects it from physical damage in the event of a fire, and the extensive fruitbody production after a fire may reflect "a successful fungal escape from a dying host where the fungus no longer can maintain its biotrophic association".