The asexual (imperfect), or conidial stage of U. craterium is a plant pathogen known as Conoplea globosa, which causes a canker disease of oak and several other hardwood tree species.

Urnula craterium is parasitic on oak and various other hardwoods; it is also saprobic, as the fruit bodies develop on fallen dead wood.

Kupfer's macro- and microscopic analysis of tissues from these and related genera proved that U. craterium represented a genus unrelated to Geopyxis, and Fries' classification was restored.

[4] The genus name means "little urn"; the specific epithet is derived from the Latin cratera, referring to a type of bowl used in antiquity to mix wine with water.

The fruit bodies begin from dense, black mycelium on the surface of oak branches in contact with the ground.

Starting out as rolls of cylindrical tissue 1 or more centimeters long and 3–4 mm wide, they expand slowly over the winter, and grow rapidly in the spring when the weather becomes warmer.

[15] Urnula craterium grows singly or clustered together, usually attached to sticks and branches (especially oak) that are partially buried in the ground.

One of the first fleshy fungi to appear from March to May, U. craterium has been dubbed a "harbinger of spring",[18][19] and is sometimes encountered under melting snow.

[11] Michael Kuo, in his 2007 book on edible mushrooms, lists the taste as "mediocre", and comments "the devil's urn is not as bad as I thought it was going to be.

However, none of these isolated compounds inhibits the aspen pathogens in vitro, suggesting the true nature of the antifungal mechanism in the devil's urn has not yet been resolved.