These rare living fossils provide clues to what the Earth looked like 3.5 million years ago

Stromatolites growing in Hamelin PoolCredit: Paul Harrison with GFDL permission; CC-BY-SA-3.0

Stromatolites are layered sedimentary formations that are created by microorganisms. The stromatolites resemble rocks.

The microorganisms cause the adhesion of sand and other rocky material so that "microbial mats" are formed. The microbial mats are sheets of microorganisms. The sheets can build up layer by layer over a period of time and can serve as a record of the types of microorganisms that existed in the past.

Fossilized stromatolites can even produce evidence of the organisms that lived on Earth millions of years ago.

According to Atlas Obscura, some stromatolite fossils are 3.5 billion years old but there are also living stromatolites that exist today. And Australia is one of the few places in the world that is home to living stromatolites.

The stromatolites of Hamelin Pool situated on the coast of Western Australia are the oldest type of photosynthetic organisms in the world. This is because they are formed by cyanobacteria.

Cyanobacteria are blue-green algae that have been known to exist for 3500 million years. They are the oldest type of photosynthetic organism and they predate plants.

The stromatolites of Hamelin Pool in Australia are part of Earth's evolutionary history. The Hamelin Pool location is only one of two places in the world where living stromatolites exist. They grow at a maximum of 0.3 mm per year. In addition, they form the biggest colony of living stromatolites on Earth.

Efforts are being made to made to ensure that they continue to grow undisturbed. Visitors are allowed to see the stromatlites. Currently, the area is under repair after damage from a hurricane so there is only limited viewing.