The title of "Earth's First Animal" may be awarded to sea sponges, American scientists say. A new study from the Massachusetts Institute of Technology (MIT) reveals that sea sponges were present even before most animals appeared millions of years ago. New genetic analyses confirm that a mysterious molecule found in rocks that are about 640 million years old are from sea sponges. This means that sea sponges were already present before the Cambrian explosion, a period that began about 540 million years ago, when most ancient animals were reported to appear.
