An article published in the journal “Scientific Reports” describes a research on the biggest system of stromatolites existing today. In Hamelin Pool, Shark Bay, Australia, an international team led by the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science collected data between 2012 and 2014 to map eight “stromatolite provinces” each characterized by distinct morphological structures, many of which were previously unknown. The microbes that live in those communities offering clues to those that lived in the first part of Earth’s history.

Stromatolites are sedimentary structures whose name is a made by the Greek words that mean “mat” and “stone” because they are formed from accumulations generated by microbial mats. The earliest evidence of this type of stromatolites date back nearly 3.5 billion years ago. This means that there are fossils of stromatolites crossing about three-quarters of Earth’s history.

The microorganisms that produce stromatolites are similar to those that in the Precambrian were very abundant and generated the primordial oxygen in the Earth’s atmosphere. It was a revolutionary change that was a key for the evolution of all complex oxygen-breathing organisms. However, they became victims of the world they contributed so much to create and today their presence is limited to a few areas such as Hamelin Pool.

Today’s stromatolites are found in rather extreme environment, in very saline seas where competing microorganisms that form them with corals and algae is limited. The climate changes taking place in the seas threaten these ecosystems so these these microbes’ long-term survival is far from certain. Erica Suosaari, the lead author of the article, pointed out that this is the time to study the Shark Bay stromatolites exactly because they’re vulnerable.

Although today’s stromatolites are rare, ecosystems such as the Shark Bay one are complex, with a variety of morphological structures. The microorganisms that form them also have a great variety from the taxonomic point of view. In short, they’re small and vulnerable ecosystems but they’re still rich.

The study of today’s stromatolites can give us an idea of ​​how life forms were a few billion years ago, in the days when life forms with a certain compexity had just evolved on planet Earth. Comparisons with the oldest fossils help us understand what primitive microorganisms from the Precambrian might have been like. In the end, this type of research provides at the same time information about the changes that will determine the future and about the most distant past of life on Earth.