Pikaia is now an extinct, ancient chordate animal, acknowledged from the Middle Cambrian Burgess Shale of British Columbia. It is believed to swim like an eel and resemble it much the same. It had the basic body shape, which still has its stamp on the next several generations. Several scientists believe that Pikaia gracilens is one of our ancient ancestors. It is closely related to animals with backbones that range from fish to amphibians, birds, mammals, and reptiles. Its fossil, the primitive cephalochordate, dates back 500 million years ago.