Hallucigenia sparsa was a spiked, 14-legged worm that lived in the Cambrian sea. It was originally described as an “evolutionary misfit” because scientists had been unable to link it to modern-day animals. Now, reporting in Nature, researchers explain how the strange-looking creature might fit into the family tree. Paleontologist and co-author Martin Smith describes how the claws of the worm helped to unlock the mystery.