How old??!

I've been learning about lichens in preparation for the next OPAL Survey, which involves looking at lichens to assess air quality (visit air survey page). I have to confess that I knew very little about lichens until a couple of months ago, despite them being present nearly everywhere I look now! Below is Xanthoria parietina, which is a nitrogen-loving species

Xanthoria parietina

Lichens are half algae and half fungi, and grow on trees, rocks, soil, concrete, gravestones, metal... basically anywhere they have long enough to get established. They are extremely slow growing, some species only growing by 1mm per year! The oldest specimen in Britain is thought to date from 1195 AD! It's on a stone circle in Oxfordshire - has anyone seen it? And if so, can you post a photo of it?

I was really impressed with the age of that lichen, and then I found out that some specimens in Lappland may be 9,000 years old.....