Aysheaia was a genus of wormlike creatures with legs. Similar animals known as velvet worms (Onychophora, ‘claw bearers’) live to this day in decaying tree trunks in tropical forests. But Aysheaia and many other wormlike animals with legs lived in the sea during the Cambrian and are thought to have been the ancestors of both velvet worms and arthropods.

Aysheaia had a long body and short, thick legs. Most of the fossils have been found with fossil sponges, which Aysheaia probably fed on but which may also have served as protection against predators.