Sea sponges were earth's 1st animals: Research
Researchers at the Massachusetts Institute of Technology have claimed that sea sponges were likely the first animals on earth. Sea sponges are the source of a molecule found in 640-million-year-old rocks, which predate the Cambrian explosion, researchers said. Cambrian explosion was an evolutionary period that began around 540 million years ago, during which a large number of new animals appeared.