The enigmatic species of the Ediacaran

Animal, vegetable or something else entirely? For decades, researchers were baffled by fossils of bizarre living things that dated back to the Ediacaran period — around half a billion years ago. But recent evidence suggests that some of these alien-like species were in fact animals — including ones that had guts, segmented bodies and other sophisticated features. Researchers are using these finds to re-examine a pivotal event in evolutionary history: the Cambrian explosion.