Approximately three billion years old, stromatolites are one of the earliest-known life forms on Earth - predating even the dinosaurs. The primitive blue-green bacteria usually live in salty water and slightly warmer climes; there are recordings of the bacteria at sites in Australia, Brazil and Mexico.
'It's kind of like finding a penguin in the Mediterranean,' joked Giant's Causeway Area Ranger, Dr Cliff Henry. 'To find them in any cool climate, never mind on our doorstep here at the causeway, is truly astounding.'
Although they have a complicated sounding name, stromatolites are quite simple organisms compared to other life forms. Since they are a bacteria, their cells do not have a nucleus like animal, plant and fungi cells. Stromatolites are important evidence of the evolution of lifeforms - namely, why and how the tree of life branched into three domains: the Bacteria, Archaea and Eukarya. They have the ability to help us understand the beginnings of human life on earth.
'Stromatolites appear to need very particular conditions in order to exist,' explained Cliff. 'At the Giant's Causeway, they are found in shallow pools, above the normal tidal flow, that have freshwater flowing through them. It is possible that this may contain dissolved calcium compounds.'
Keeping them safe
While Cliff was happy to speculate about how these organisms came to reside in causeway rock, the precise requirements and conditions for stromatolites to exist will only be known after extensive research.
Conservationists have advised that stromatolites be offered a level of protection lest they be unwittingly destroyed. The National Trust is overseeing the preservation of these stromatolites at the Giant's Causeway.