[fairplay]

I do a lot of conservation work on heathland clearing pine and birch (sorry chap's, but it's got to be done) and come across 'Fomes' or Root Rot quite often and the photo certainly looks that way to me. I think I have seen it too with birch but it could be attached to hidden pine roots or remains of a pine stump and as you probably know, birch comes up in no time and seeds readily germinate and grow almost anywhere,including old stumps and even in the crutch of the mother tree with the roots growing down the trunk and into the soil resulting in some fantastic shapes after mum has rotted away. Sorry, I got a bit carried away there. Fairplay.