Here’s how it works. With five eyes, a backward-facing mouth, and a long, claw-tipped trunk where its nose should be, Opabinia regalis is one of the strangest-looking celebrities of the Cambrian ...

This 508-million-year-old organism, named Opabinia regalis, seemed an isolated expression of evolution running riot back in the Cambrian period—before a mass extinction swept such oddities away.