Stromatolites at Shark Bay

The microbial mats in Shark Bay are, archaeologically, remnants of what Earth was like at some point in the distant past. Scientists theorise that these types of bacteria dominantly inhabited the Earth and were responsible for the formation of complex life.

Currently the belief is that these bacteria donated the genes that let them photosynthesise to other organisms. After they gave rise to complex plant forms though, their descendants transformed the surface of Earth to be the relatively^[1] temperate environment we know today. After a while^[2], the same conditions that allowed stromatolites to thrive no longer existed.

Nowadays they are sparsely distributed, usually only in extreme conditions, including the variable temperatures and high salinity in the tide-affected Hamelin pool in Shark Bay. These hardy organisms created the Eden that we live in today.