An extremely rare narwhal skull with double tusks. There are only about 10 other bones like this in the world. Narwhals are a rare arctic whale. It is challenging enough to see one with one tusk. It is almost an impossibility to actually catch one with two tusks. Biologists estimate that there are only 1 in every 1000 Narwhal who actually have a double tusk. They are uncertain of why this phenomenon exists. They are even more uncertain why these sword like tusks occur on the whale.