A Window Into Early Earth

Even though it is permanently covered in a layer of ice, Antarctica’s Lake Untersee is home to a vibrant population of photosynthetic microbes. These little guys form the incredible conical structures you see in that photo above… aren’t they surreal? The cones – called stromatolites – are actually built by layers upon layers of bacteria and minerals.

Microbes can’t create visible fossils like a dinosaur’s footprints or bones, but when they form large-scale structures like microbial mats or stromatolites, those structures can become preserved in the fossil record. In fact, fossilized stromatolites provide our oldest evidence of life on Earth more than three billion years ago.

For about two billion years, stromatolite-forming microorganisms were the dominant – or even the only – life on Earth. These days, stromatolites are developing in only a few underwater environments. They grow into many different shapes and sizes, but until Dale Andersen and his team went SCUBA diving in Lake Untersee, nobody had ever seen modern stromatolites that look so much like those ancient ones! Perhaps – if we’re lucky – studying the conditions in Lake Untersee will reveal more about what Earth was like when the first lifeforms were taking hold.

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