Scientists have found evidence of the earliest animals on Earth in rocks about 541 million years old.
- Researchers detected chemical fossils known as steranes in these ancient rocks.
- The steranes indicate that sea sponges (demosponges) were among the first animals in the oceans.
- The find shows animal life existed before the Cambrian explosion, the period when many animal groups evolved rapidly.
- It also suggests these early animals lived in oceans with low levels of oxygen.