Evidence for single-celled life on Earth stretches back over 3.5 billion years. However, the oldest evidence for animals moving about on Earth is from the Ediacaran Period, which lasted from around 635 to 541 million years ago. The trails they made aren't footprints, but are instead more likely the results of creatures wriggling along the surface of the sediment. Fossils from the Ediacaran include bizarre life forms that are poorly understood. Many of these fossils are narrow and long, and it can be difficult to distinguish fossil trails from impressions of the animals' bodies. Nevertheless, some of these fossils appear to provide some of the earliest evidence for animal locomotion on Earth. The photo shows a fossil trail that was found in Newfoundland, Canada, and is thought to have been made around 565 million years ago in ocean sediments. The animal that made this track is unknown, but one group of scientists has suggested that the locomotion trace is similar to trails made by modern sea anemones.