This is a closeup of it and I'll put it in its full context after the fun...
I have missed posting, but I have been pooped and I don't care what anyone else says, this posting stuff is exhausting! ;-)
I just noticed the scoring on the upper right, and it is clearly, at least to me, rodent teeth marks! Neat, something tried to eat it....
It was 'growing?' -don't know if thats the right term- under the roots of a tree and it had that fungal look, very organic in some way, but it also looks calcified and the blue-green cracks and lines have a distinctly mineral look...