The Dead Tree

Deep in the woods above Dunrobin Castle stands this dead tree. That it's in a clearing suggests that the foresters ensured that it had plenty of space, which may indicate it was something slightly special, perhaps an oak.

Look at a point about two metres above the base of the trunk where there is....

....a large growth. It intrigued me, so I took several photographs in the hope of finding out what it is, but my searches on the internet have been in vain. What intrigued me the more is that, at top left of the growth....

....a fungus is flourishing. Is the fungus part of the growth, or did some spores just happen to land in the crack between the growth and the trunk and thrive there?

Like so many questions I have about the wonderful world in which we live, I may never know the answer. Do I mind? Yes.