Nef. 17th c. South German. Ivory. Also known as the “Rothschild Nef,” because it was in their collections for many years. Attributed to Georg Pfründt. Image source: Sotheby’s. Fair use license. via http://www.alaintruong.com/archives/2016/12/20/34711869.html
Note: I am comfortable using these in my blog post because they were carved 400 years ago. They could be narwhal, elephant, or walrus ivory. It does not specify.