From very close it does look like algae. I haven't put mine under the microscopepulled a piece of mine out and put in a mason jar. heres some close ups
2nd pic is a close up of the attachment endView attachment 1451615View attachment 1451614
We are pretty far ahah. It's growing on manzanita(not even sure)If you were closer, I would let you use my giant computer microscope. What kind of wood is it?