Lichen

I went out to find some cool lichens today and wasn't disappointed.

Lichens consist of a fungus and a green algae or cyanobacteria living in symbiosis. Some have all three. The fungus is dependant on the food fixing and shape giving properties of the algae/cyanobacteria. What the algae gets out of it is less clear.

I think this one might be Xanthoria polycarpa from the excellent British Lichens website.

55mm f5 I think