The real survivor is indeed a cephalopod, but nautilus rather than octopus. Still living in the Pacific, present-day nautiluses are little changed from 200 million years ago. Living in coiled shells, they’re now scavengers. They have simple eyes and a cluster of tentacles, and they move up and down, from the deep sea to shallower water, in a rhythm that’s still being studied. They seem to stay higher in the water at night, deeper in the day.
