Narwhal tusks are twisty, magical mathematical marvels

Narwhal (Monodon monoceros) tusks may not really be magical, but they do have some mathematical magic. Their tusk is actually made up of two spirals (or helices) instead of one. The tusk’s outer structure twists to the left, while the interior twists in the opposite direction. “The really special part is that these helices always have the same handedness—similar to if all [people] only had left hands,” Henrik Birkedal, a chemist at Aarhus University in Denmark, tells