Stag antler and horn.

Stag antler looks a lot like bone. It has marrow on the inside which is not suitable for carving. The part where the antler is attached to the head is more or less solid and can be used for carving. Antler is hard and tough.

Horn is in fact hair. Like your nails. Fibrous and very tough.

Both are very difficult materials to carve. I use cutting tools as well as scraping tools.