Until a few days ago, on my inestimably long list of unknown unknowns was the fact that the chewing organ of sea urchins, which is composed of five teeth and a fleshy tongue-like structure, is called Aristotle’s lantern because it was described by Aristotle in his History of Animals as being similar in appearance to a horn lantern.
Among other things, sea urchins eat brown algae, a dietary preference to which I can relate, as I’ve likely at some point eaten ice cream thickened with alginate, a polysaccharide extracted from brown algae. When I next run into a sea urchin in a social setting, I will be sure to explore this common ground.
