‘Yes, I’ve noticed that growth too, but to be honest if you want to know more you need to talk to lichen people, there are a few that specialise in nothing else and they are the only ones who really understand lichens.’
The reason for their complexity is that they are symbiotic, they are an association of algae and funghi, which take on about 15,000 known forms. In fact the debate still goes on within the scientific community about how they should be classified at all. Sometimes maybe there is more joy to be had in just looking at nature and not trying to get too clever!