This is the canine of a walrus, Odobenus rosmarus, from the permafrost of Alaska. Judging by the moderate size, this may be from a female walrus. Walrus tusks (but not cheek teeth) are open-rooted; that is, the tooth pulp-cavity is not closed as it is in many other taxa of mammals. Think of the continuously growing incisors of rodents and lagomorphs.
The term used to describe this condition is "hypselodonty" and is usually applied to mammal teeth. Other taxa with hypselodont teeth include xenarthrans, rabbits, some rodents, and a few ungulates