This example was found on a rough weathered boulder on the north side of Lower Hartor Tor. They appear to like to find a small niche or crevice that provide them both protection and a source of mositure.
A lichen is a compound organism comprising a fungus, an alga and sometimes a cyanobacterium, co-existing in a mutually beneficial partnership. The algae and/or cyanobacteria are protected from the environment by the fungal body, and the fungus receives nutrients from the algae which are produced by photosynthesis. The cyanobacteria also have the ability to fix nitrogen. This complex relationship enables lichens to colonise a very wide range of habitats.