The lichen has a umbilicate thallus that is dark brown to greyish-brown in colour, ranging greatly in size and featuring a single folded leaf with a torn margin.

[2] A study conducted on rock-dwelling lichens in a coastal barren of Nova Scotia revealed that Umbilicaria muhlenbergii was predominantly found on the back faces of boulders, and its abundance gradually increased as one moved away from the shoreline.

[6] Adding pieces of the Umbilicaria muhlenbergii to fish broth was a practice adopted by the Woodland Cree (Sakāwithiniwak) people from southeastern Saskatchewan to transform it into a thick soup.

[2] Umbilicaria muhlenbergii can grow in different forms depending on its environment: it occurs as fungal hyphae in lichen thalli, and as yeast cells when grown in axenic culture.

A 2020 study found that conditions of nutrient limitation, hyperosmotic stress, and contact with algal cells induced the dimorphic change in U. muhlenbergii.