The earliest morphological traces of life on Earth are often highly controversial, both because non-biological processes can produce relatively similar structures and because such fossils have often been subjected to advanced alteration and metamorphism. Stromatolites, layered organo-sedimentary structures reflecting complex interplays between microbial communities and their environment, have long been considered key macrofossils for life detection in ancient sedimentary rocks; however, the biological origin of ancient stromatolites has frequently been criticized. An article released Friday in the Geological Society of America journal Geology uses a range of advanced two- and three-dimensional analytical techniques to establish the biological origins of Earth's oldest stromatolites from the 3.48-billion-year-old Dresser Formation, Pilbara, Western Australia.
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