Crustose Lichen

Is it grey/green, or is it coloured?

Crustose lichens are typically strongly bonded to their substrate, be it rock or bark. They are very slow growing, of the order of 0.5mm per year, so a large one could be hundreds or even thousands of years old.

Lichens are typically greenish in colour, reflecting the chlorophyll of their algal component. However, some crustose lichens are pigmented, particularly the classic orange lichen of the eastern Tasmanian coastline.

This site is a photographic field guide rather than a rigorous biological classification of Tasmanian lichens. For further information on the formal classification of  lichens, see this article from the Australian National Botanic Gardens.