1.6-billion-year-old steroid fossils hint at a lost world of microbial life

Molecular fossils found in ancient sedimentary rocks have unveiled a lost world of primitive eukaryotes that dominated aquatic ecosystems from at least 1.6 billion to 800 million years ago.

The findings, published June 7 in Nature, come from laboratory analyses of rock samples from around the world that revealed remnants of primitive compounds called protosteroids. The majority of these molecules, which form in the process of creating steroids, were likely produced by primordial eukaryotes, relatively complex life-forms that today include animals, plants, algae and fungi, the researchers say.