Australian stromatolites – Wonderous building blocks of life on Earth

Stromatolites are some of the oldest forms of life on this planet.  Without them it is very likely that life as we know it would not exist, it would be something extremely alien to us.  Australia is home to at least two impressive colonies of these microbes and I visited both.  For anyone at all interested about our planet you should go and visit them because even though they’re very old they might not have much time left.

Bill Bryson’s absolutely superb A Short History Of Nearly Everything introduced me to stromatolites.  His enthusiasm for these strange cyanobacteria, AKA blue-green algae, seemed a bit over the top at first but when I grasped just how important they were to life as we know it I became hooked on the idea of seeing them in their habitat.

Stromatolites usually live in hypersaline (extremely salty) bodies of water but they can be found in cave systems as well.  Australia, in all its natural magnificence provides two of these locations in the Jenolan Cave system near the Blue Mountains National Park in New South Wales and at Hamelin Pool in Shark Bay, Western Australia.  Two easily-reached destinations.

These tiny microbial colonies helped shape Planet Earth by constructing stony nodules from biofilms they excreted.  They trap other mocrobes and add them to their super-structure so what to them would appear to be mile-high skyscrapers, to us they appear as half-metre to two-metre high rock lumps.  From these the cyanobacteria process sunlight and excrete oxygen.  It is reckoned that stromatolites provided the majority of Earth’s early oxygen and paved the way for other forms of life which depend on it.  Quite literally we owe them our existence.

The Jenolan Caves’ stromatolites


The stromatolites at Jenolan are rare, even among rare stromatolites, because they do not form in super-salty water.  They exist as a consequence of the dripping of calcium-rich water from the cave ceilings and they form some truly Alien-looking shapes…

Stromatolite, Jenolan cave, Australia

Jeez, they really do look evil, Stromatolites at Jenolan, Australia

Hulking xenomorph forms in the dark of Jenolan caves, Australia

The whole cave system is incredible here.  They stretch for many kilometres with chambers carefully lit to highlight the staggeringly beautiful natural formations throughout.  It’s only an hour or so from Katoomba so really this site should be far more touristed but the lack of crowds help to give justice to the whole area.

Hamelin Pool Marine Nature Reserve, Western Australia


We were touring from Perth to Exmouth on a guided tour, Hamelin Pool Marine Nature Reserve was my primary interest for the whole trip.  Again, it might not be much to look at – dozens of strange rocky nodules lying just under the water’s surface – but when you grasp that those little bubbles you can see streaming from them to the surface are part of the same process that allowed mammals to exist in the first place, then it really is quite impressive in its simplicity.

Stromatolites in Hamelin Pools, Shark Bay, Western Australia

Jellyfish at Hamelin Pool

Sea stromatolites at Shark Bay

Monkey Mia is the main local tourist attraction and yes, I did have superb time hand-feeding a dolphin, but these little lumps are more meaningful by far.  There’s a boardwalk out over the stromatolites and I could have spent several hours just lazing around thinking about things and taking in the views.  For me this is a very important site in Australia.

So as you can see they are quite odd-looking in the water too.  A bit like coral formations but far more important.

Sadly the melting ice-waters of the poles and glaciers is desalinating the oceans.  That will make the habitat of these salt-loving colonies retreat and eventually become unsuitable for their form of life.  The stromatolites will become even more like marine fossils than they already are.  An incredible link to early life on Earth will be lost and I for one will mourn them.

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