The Cambrian oceans hosted a riot of evolutionary novelty. Over a seabead burrowed by penis worms and tread by living pincushions, multi-eyed invertebrates swung their schnozzles after prey and our closest, archaic relatives squirmed through the water. Largest of all were the anomalocaridids – cousins of arthropods that flapped through the water on segmented wings and were equipped with a pair of “great appendages” hanging below a pineapple-ring mouth. Their size and flexible, spiky arms have made them dead ringers for apex predators in the eyes of paleontologists, but new research has cast at least one of these mind-bending invertebrates as a filter-feeder that was