What is a Narwhal's horn made out of?

Answer 1

The narwhal's horn is actually a tooth.

Answer 2

According to this site it is made of ivory.
http://www.swanseaheritage.net/article/gat.asp?ARTICLE_ID=614&PRIMARY_THEME_ID=2

Answer 3

Thanks so much :)

Answer 4

To take the answer a little further. Ivory is dentin. Dentin consists of the area of the tooth above the tooth pulp and under the enamel. It contains a mixture of minerals, collagen, and water. The mineralized tissue is much stronger and more durable than bone.