I see this everywhere on the Canadian Shield in Ontario, for context
Lichen.
When purchasing my previous home, I asked the inspector about a suspicious goopy substance on a window.
"Goop," he labeled it, then advised me not to worry about it.
He was right; it was gone by the time we closed on the house and, as far as I could tell, never returned.
So anyway, are you that inspector? It would be nice to give him credit.
๐
Tried using Seek by iNaturalist but it couldn't get any more specific than the rock shield lichens genus:
Looks to be in the family Parmeliaceae, which is pretty large. I'm really just beginning to learn how to ID but I might start at a genus like Xanthoparmelia or similar.
A community for lichen enthusiasts to post photos, questions or to discuss the science of lichenology.