3D X-ray imaging unlocks the secrets of the narwhal's spiral tusk

Aug 20 : In the Middle Ages, narwhal tusks were sold as unicorn horns blessed with magical powers such as neutralizing poisons and curing diseases — prized possessions of monarchs and nobles worth more than their weight in gold. They provided no such powers, of course, but even today remain objects of mystery.Researche

The study, published in the journal Nature Communications, explains how it's actually two opposing spirals that counteract each other and allow the tusk to grow straight.

A large international team of researchers announced they had solved a long-running mystery about narwhal tusks: how they get their uniquely spiralled yet arrow-straight form.

New study finds that the tusks have not one but two spirals, twisting in opposite directions.