"The tusks had long been part of Inuit culture. Then starting around A.D. 1000, Viking traders began selling the tusks, which they found surfacing on the shores of places like Greenland, to other Europeans. Historians have found evidence of the tough tooth being fashioned into weapons for hunting and fighting."
"The tusk of the now-endangered Narwhal can grow anywhere from five to ten feet in length and is a sensory organ, covered with nerves on the outer part of the tusk. So that tusk (which is actually a long, spiral tooth) doesn't just fall out or shed naturally. For every Narwhal tusk, there's a dead Narwhal out there somewhere. For the Inuit, they use the occasion to make hunting weapons from the tusks, and the length is ideal for making a spear."