Something a little different today. Lichens are composite organisms consisting of a symbiotic relationship between a fungus and either an algae or bacteria. Lichens grow in some of the most inhospitable parts of the world and under extreme circumstances. This particular one was growing on our roof until dislodged, possibly by a Magpie. It's called Xanthoria parietina.
The leathery surface of this lichen is formed by fungal hyphae (the 'root-like' structures of a fungus). This skin is essential to limit water loss and so prevent dehydration in the arid conditions of walls, roofs, etc.