Fruit bodies are gelatinous, pale to dark brown, up to 7 cm (3 in) across, and seaweed-like (with branched, undulating fronds).

The basidia are tremelloid (globose to ellipsoid, with oblique to vertical septa), 13 to 18 by 12 to 16 μm, usually unstalked.

The basidiospores are subglobose to broadly ellipsoid, smooth, 6.5 to 10.5 by 5 to 9 μm, and germinate by hyphal tube or by yeast cells.

Phaeotremella fimbriata is a European species parasitizing Stereum rugosum on broadleaf trees.

Following its hosts, fruit bodies of P. frondosa are typically found on dead, attached or recently fallen branches of broadleaf trees.