For four hundred years, Europe believed in unicorns because of this animal, and this animal said nothing.

The horn is a tooth. Left canine, grown straight out through the upper lip and kept going until it's nine feet of counterclockwise spiral. Norse traders hauled them south and sold them as unicorn horn at prices that bought castles — Elizabeth I is supposed to have paid the cost of one — and at no point did anyone mention the enormous gray whale still swimming around in the dark up north, minding its business, entirely uninterested in the credit.

The tooth is wired. Millions of nerve endings run through it to the surface, which means the narwhal navigates the Arctic by tasting the water with a tooth turned inside out. Nobody asked it to do this.

It dives a mile down, under solid ice, in total blackness, for twenty-five minutes at a time. There is a knocking sound it makes down there that no one has explained.

Let them think you're a myth. Correcting them was never the assignment.