Lichens are made up of two or more closely interacting organisms, first one is a fungus, the other one is an alga and/or cyanobacteria. Alga and cyanobacteria in this relationship are called photobionts. The fungus itself is not capable of photosyntesis that would provide it with energy and because of this, it needs the alga or cyanobacteria. On the other hand, the fungus provides optimal living conditions for a long term, stable association with their photobionts.
Lichens may be used, among other, as a dye and when I look at these photos, it doesn’t suprise me.