A few weeks ago, during a trip to the Scripps Institution of Oceanography’s Birch Aquarium, I bumped into a nautilus. More or less. Admittedly there was an aquarium pane and many gallons of water between me and the cephalopod, but I was still surprised to see the archaic creature bobbing along in the dark tank.

I had seen photos of the shelled mollusks plenty of times, but seldom the actual animals. I hate the term “living fossil” – the phrase is more of a subjective judgment of a creature’s place in nature than a useful descriptor – but, I have to admit, the nautilus did look as if it was a