Is this a whale's tooth?

[harrywagner]

Originally Posted by Henk

Ivory?

Maybe. Here is what professor Google says:

Thirty teeth of the sperm whale can be used for ivory. Each of these teeth, up to 8" long and 3" across, are hollow for the first half of their length. Sperm whale ivory is easily confused with walrus ivory, as both have two distinct layers. The inner layer of sperm whale ivory, however, is much larger.

I don't think it is bone, but I could be mistaken.