|Click picture to see Pikaia swim|
Pikaia was first described as a polychaete worm by Walcott, but scientists now think Pikaia was an early chordate, resembling the modern day lancelet. It probably swam like an eel, near the bottom of the ocean.
Pikaia may have been the ancestor of all vertebrates, including humans. Although Pikaia had a notochord, it was not a vertebrate because it did not have a backbone.