Winter Pictures – Clarkson’s Wood
I think this is Hoof Fungus (Fomes fomentarius) a perennial bracket fungus growing here on a fallen birch tree.
Possibly the top of a Birch Polypore fungus (Piptoporus betulinus)
Possibly the holes of some sort of wood-boring insect . The green moss looks like Rough-stalked Feather-moss (Brachythecium rutabulum)
The branches have tiny fungi on them if you look closely