Underwater ‘Lost City’ In Greece Turns Out To Be Act of Nature

Ancient underwater structures thought to be remnants of a "lost city" were actually created by nature, researchers said.

Divers found the structure off the Greek island of Zakynthos. It had what looked like cobblestone floors and bases of Greek colonnades, which made it appear to be remnants of a long-forgotten civilization.

But in a study published in the journal Marine and Petroleum Geology, researchers from the University of East Anglia and University of Athens found that the structures were actually a result of a geological phenomenon millions of years ago. 

"There were what superficially looked like circular column bases, and paved floors, but mysteriously no other signs of life - such as pottery," lead researcher Julian Andrews wrote in a statement published in Time.

Andrews and his team of researchers analyzed the formations and discovered that the structures were the work of microbes.

"This kind of phenomenon is quite rare in shallow waters. Most similar discoveries tend to be many hundreds and often thousands of meters deep underwater," Andrews said.

Researchers said in a press release that the structures were likely a result of their location, which is directly a subsurface fault hidden by the seabed where methane seeps out of the Earth's crust in different ways.

The carbon contained in the methane is used by microbes in the sediment as fuel, and this changes the composition of the sediment and forms a kind of cement. Water currents erode the surrounding sediment over time, which reveals the harder and naturally-formed structures.

According to researchers, the different forms were likely the result of the various formations of the methane leaks. The process, which is known as concretion, commonly occurs in ocean depths and rarely happens in shallow waters. Therefore, it is easy to mistake these formations for human-made structures.

When Greek authorities examined the site after it was discovered by snorkelers, they found no signs of human life, such as pottery, shards or coins, or any indication that it was human-made.

The site is near Alikanas Bay and was examined by the Ephorate of Underwater Antiquities of Greece.