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 a 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.
Stromatolites are formed by a blue-green algae that excretes carbonate to form a dome-like structure. Over thousands of years these build up into a hard rock that continues to grow. Stromatolite fossils have been dated as far back as three and a half billion years. 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.”