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In Images: The Oldest Fossils on Earth

Shark Bay, Australia

Stromatolites, like those found in the World Heritage Area of Shark Bay, Western Australia, may contain cyanobacteria, which were most likely Earth's first photosynthetic organisms.

(Image credit: Rob Bayer/Shutterstock)

Some of the more distinctive ancient fossils are stromatolites, which are cone shaped rock-structures that pile up as the byproduct of cyanobacteria metabolism. In modern day, some of the most striking examples are found in the most westerly tip of Australia, called Shark Bay. Here, huge fields of stromatolites are lapped by the salty ocean waters and fed by bright sunlight.

Pilbara region

Pilbara

(Image credit: NASA Earth Observatory)

Scientists have found 3.43-billion-year-old fossil stromatlites in the Pilbara region of Australia. Here, a landsat image of the region.

Stromatolite layers

Pilbara stromatolite

(Image credit: Paulo Afonso/Shutterstock.com)

Here, layers from one of the Pilbara stromatolites.