I first found this here two years ago. Since I was in the area, I decided to see if I could re-find it. On at least a half dozen trees, including one a couple hundred yards to the west.
On NE facing cliff along river. Growing alongside lots of snakewort, nostoc, and various mosses.
Guess to species
Growing on metal, thin, closely attached, infrequent colonies.
with Psorula rufonigra.
On west facing cliff about 15 feet away from the shoreline on small lake. First time seeing this species away from Superior's shoreline.