It produces blackish, frondose, gelatinous basidiocarps (fruit bodies) and is parasitic on the mycelium of Stereum rugosum, a fungus that grows on dead attached and recently fallen branches of broad-leaved trees.

Phaeotremella frondosa is a similar-looking but paler, brown species on broad-leaved trees and occurs in North America as well as Europe.

It was not until molecular research, based on cladistic analysis of DNA sequences, revealed that Tremella foliacea sensu lato covered several similar but distinct species, that the name Phaeotremella fimbriata was distinguished and recognized in its current sense.

[1] Fruit bodies are gelatinous, dark blackish brown becoming black, up to 4 cm (1.5 in) across, and seaweed-like (with branched, undulating fronds).

Following its hosts, fruit bodies of P. fimbriata are typically found on dead, attached or recently fallen branches of broad-leaved trees, particularly alder.