Since I’ve posted about stromatolites before, I hope that readers remember what they are. As a refresher, though, they’re the oldest convincing traces of life on earth: fossilized colonies of cyanobacteria (“blue-green algae”) which date back 3.5 billion years ago—only a billion years after the Earth had formed. While fossilized stromatolites have been found in many places, living ones can exist only in a very few places on Earth. Wikipedia notes:
Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where extreme conditions due to high saline levels exclude animal grazing. One such location is Hamelin Pool Marine Nature Reserve, Shark Bay in Western Australia where excellent specimens are observed today, and another is Lagoa Salgada, state of Rio Grande do Norte, Brazil, where modern stromatolites can be observed as bioherm (domal type) and beds. Inland stromatolites can also be found in saline waters in Cuatro Ciénegas, a unique ecosystem in the Mexican desert, and in Lake Alchichica, a maar lake in Mexico’s Oriental Basin. Modern stromatolites are only known to prosper in an open marine environment in the Exuma Cays in the Bahamas. Stromatolites can also be found in the hyper-saline inland lakes on San Salvador Island, Bahamas.
According to the BBC, though, living stromatolites have just been found in a place frequented by bazillions of tourists—the Giant’s Causeway, a formation of basaltic hexagons in Northern Ireland:
In a small grey puddle tucked into a corner of the world famous Giant’s Causeway, scientists have made an extraordinary find.
A colony of stromatolites – tiny structures made by primitive blue-green algae.
Stromatolites are the oldest known fossils in the world.
The tiny algae or bacteria that build them are also thought to be the most ancient life form that is still around today, after more than three billion years.
What makes the discovery in Northern Ireland so remarkable is that until now these structures have been found mainly in warm and often hyper saline waters which discourage predators.
The stromatolites in the Giant’s Causeway are in a tiny brackish pool, exposed to the violence of waves and easy prey to the animals that are already living amongst them.
The find was purely accidental, suggesting that perhaps living stromatolites occur in other places but simply haven’t been found. It’s also a very young colony—only one layer thick. The ancient fossilized ones (see below) are composed of many layers of bacteria separated by sediment.
The colony at the Giant’s Causeway on Northern Ireland’s wind-swept north coast was found by accident.
Scientists from the School of Environmental Sciences at the nearby University of Ulster were looking for very different geological formations when Professor Andrew Cooper spotted the stromatolites.
“I was very surprised”, explained Professor Cooper.
“I was walking along with a colleague looking at something else. Out of the corner of my eye I spotted these structures which, had I not seen them before in my work in South Africa, I probably wouldn’t have known what they were.”
The colony is very young, just a layer thick, so it’s recently formed. One thing that is puzzling scientists is why its chosen this spot.
“There is some unusual set of circumstances that occurs just here that doesn’t occur even 10 metres away along the beach,” said Professor Cooper.
The place is sure to be flooded with gawkers looking at this ancient life formation, so I hope the local authorities are doing something to protect the area.
Here are living stromatolites in Shark Bay, Australia:
And some fossils, clearly showing the layers: