Thanks for your reply, you are right about the mosses. I also enjoy how Lichen looks like. I did a little research to get an idea of what one could do with Lichen and check this out: with specific types you can make medicine, food and dyes. I also had an interesting read on the US National Library of Medicine's website about the history of Lichen usage by humans, common practices and known benefits. Here's the link to that article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5320728/
RE: What's that green stuff everywhere? It's Lichen!