הזיהויים של gbperlmutter

The observation is for the protrusions on the upper surface of this Dermatocarpon (for which a separate observation has been made: https://www.inaturalist.org/observations/192663915).

I conjecture that they are the result of a lichenicolous fungus, but that speculation is not affirmed by the Flora of Lichenicolous Fungi, 2022, the contents of which do not include the genus Dermatocarpon.

EDIT, 30 November 2023, 6:46pm Eastern Standard Time: Flora of Lichenicolous Fungi, 2022, pages 265-6, does have Tremella umbilicariae, known to parasitize species of Umbilicaria, of which Dermatocarpon is a related genus.

Physconia subaquila

https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_P/Text_P_4/Physconia_subaquila.htm

Vertical siliceous rock, east facing, with the Haw River flowing by below. The lichen is located above the highest flood stage.

The cold bedrock condensates water from the humid air above the river. The lichens and mosses in close contact with the rock also have water condensate on them, or are able to wick up the water from the damp rock. This is a special microclimate that obviously is satisfactory for a picturesque assemblage of lifeforms.