Laid down over millions of years, these rock layers contain a permanent record of the Earth's past, including the fossilized remains of plants and animals buried when the sediments were formed.

During the Proterozoic era, oxygen produced by photosynthesizing ... So what exactly were these highly diverse Precambrian creatures? Plants, animals, or of another kingdom entirely?

In a study published in Precambrian Research ... observed in primitive simple animal-like life forms such as those found in the fossils from this period,” Fru said. The complex life forms ...