In 2014‚ divers off the Greek Island of Zakynthos found what appeared to be the remains of a lost city - except researchers now believe it wasn't made by humans‚ and may have in fact been 'built' five million years ago.When the divers reported the find‚ the Ephorate of Underwater Antiquities of Greece decided to investigate‚ sending in archaeologist Magda Athanasoula and diver Petros Tsampourakis‚ who together with Prof Michael Stamatakis from the Department of Geology and Geoenvironment at the University of Athens‚ did a preliminary examination of the site.Once this was completed‚ a research team was formed in partnership between the University of Athens and University of East Anglia. What the researchers found was that it wasn't a human ruin.“The site was discovered by snorkelers and first thought to be an ancient city port‚ lost to the sea. There were what superficially looked like circular column bases‚ and paved floors. But mysteriously no other signs of life – such as pottery‚” Lead author Prof Julian Andrews‚ from the University of East Anglia's School of Environmental Sciences said in a media statement.So it is very unlikely that the structures were human made‚ instead scientists believe the smooth structures were manufactured by sulfate-reducing bacteria.“We found that the linear distribution of these doughnut shaped concretions is likely the result of a sub-surface fault which has not fully ruptured the surface of the sea bed. The fault allowed gases‚ particularly methane‚ to escape from depth‚" Andrews said.The bacteria thrives in methane that seeps up through the ocean floor around the site - altering the soil chemistry.This means that they create the sort of conditions that allow dolomite to form - in shapes that look like paving stones when the methane seepage is defused‚ or structures that looks like wheels when it is more focused. This also explains the linear distribution of the "ruin" - because it formed over a crack that allowed the methane to escape.Once the structure formed in the soil‚ it was only a matter of some erosion to expose them."The same thing happens in the North Sea‚ and it is also similar to the effects of fracking‚ when humans essentially speed up or enhance the phenomena‚” Andrews said.You can read the full research on Sciencedirect, but it requires a subscription...