Unicorn fish is living history
If a picture of a Narwhal doesn’t trigger four of the five Ws – who, what, why, where? – then you are either a marine biologist or have no imagination. Apparently, their improbably tusk can also raise the question “when?”. Like tree trunks, a layer of horn is added every year, and as narwhals can live to be 50 scientists can use the spike to glimpse back into the history of its surrounding waters.