Hallucigenia's Spikes

an ancient worm-like creature with spikes on its back
(Mary Parrish, Smithsonian Institution)

Despite the impressive adaptations of the world’s first predators, those that were preyed upon soon developed their own line of defenses. Hallucigenia sparsa, a worm, is notable for the porcupine-like spikes that covered its back—an efficient way to ward off hungry jaws.