If you are familiar with unicorn of the sea, these one fits right into the description. The Narwhal is commonly found in the Artic coastal Waters and rivers.
For the males, the average growth of would fall to about 8.8 feet. This pertains to the sword like tooth growth that has a spiral shape. Most of the scientists have no clue for the purpose of the tusks found in the male.
Perhaps, the reason would be to attract the female during the mating time or to warn off possible suitors who are coming for the female. The female has a grown tusk of his own but not as large compared to the male.
Since these creatures of the Arctic waters, they are most seen or found in the Canadian or Russian coasts. They could also be found in the Arctic Ocean and along the coasts of Canada and Greenland.