We have now 3D scanned over 100 objects in animal hard tissues for the identification resource but this has been one of the most challenging. At 2 m 60 cm it is certainly the longest we’ve tackled yet. You will have seen it on Reddit, you may know it as the unicorn’s horn but horn is the last thing it is!

The tusk of the narwhal is an overgrown upper left incisor. Once assumed to be merely a weapon with which male narwhal could joust, it is now thought that this tooth acts as a sensory organ detecting changes in temperature, pressure, salinity and particle density in the seawater.

Having a protruding tooth this length could be a liability, especially when navigating the ice of the Arctic waters where the narwhal lives. The possibility of it breaking appears very high but in its own way the structure of this tusk is every bit as magical as the fabled unicorn’s horn . This tooth has a long narrow pulp cavity running almost its entire length over which the dentine gradually forms. Each new layer is twisted to a different degree so that whilst the innermost layers are twisted anticlockwise up its length to the tip, the outer layers and cementum covering are twisted clockwise. This produces a relatively flexible but really strong material in the same way that sheets of carbon fibre are combined in the construction of aeroplane or high-class racing bike components to produce very tough structures.

Frequently found whole in collections, the distinctive shape of the narwhal’s tusk makes it instantly recognisable. In recent history the tusks were cut and worked to form quite prosaic objects, such as walking sticks or coat stands. The Inuit and other Arctic peoples used it to make spears and harpoons, whilst in Japan it was intricately carved to form netsuke. Uses even ranged to the production of coat stands! (pic below, kind permission of the Maritime Museum: Hull Museums)

In the Middle Ages it was a different story. Narwhal tusk, in the guise of the unicorn’s horn, was a prized possession of kings, princes and the major ecclesiastical establishments of Europe. The reputation of its magical and medicinal powers meant that it was valued at 10 or 20 times its weight in gold. An amulets like that in the V&A Museum, London would have been worn to protect the wearer from disorders such as epilepsy, scurvy and gout, the perils of pestilence and poison or death by violence.

The 17th C coronation throne of the Danish kings is covered in sections of narwhal tusk. They controlled the trade in these tusks from Greenland into Europe and did nothing to dispel the myths and legends of the origin and power of the unicorn’s horn – that would have been bad for business!