I think this is rock shield lichen.
Something new I've learned from Braiding Sweetgrass, by Robin Wall Kimmerer, is that lichens are a fungal/algal symbiotic relationship. I'm going to be sad when I finish this book but luckily have Gathering Moss to read too.
"When times are easy and there's plenty to go around, individual species can go it alone. But when conditions are harsh and life is tenuous, it takes a team sworn to reciprocity to keep life going forward. In a world of scarcity, interconnection and mutual aid become critical for survival. So say the lichens."
From Braiding Sweetgrass
I'm cleaning up my stash of "fabric for work projects" and am making dinosaur pillows.
More details coming soon.