Roughly 540 million years ago, something strange shows up in the fossil record: soft-bodied, often disc- or frond-shaped creatures that don't look like anything alive today. This film examines the Ediacaran biota, the mysterious organisms that appear just before the Cambrian explosion, and the paleontologists trying to work out whether they were true animals, failed evolutionary experiments, or something else entirely. It walks through the fossil evidence, imprints left in ancient seafloor sediment, and the debates over how to classify creatures with no shells, no legs, and no clear descendants. The question driving the film is simple: does complex animal life have one origin story, or did evolution try and abandon several body plans before the animals we recognize took hold? Rather than settling the matter, the film lays out competing interpretations from the scientists studying these earliest traces of complex life, leaving the mystery of the Ediacaran creatures open at the end.