When sea divers in Greece’s Zakynthos island found smooth floors and circular column bases under the sea, they thought that they have discovered an ancient civilization which has been eaten up by the huge water body. But a research report published on Friday, June 03, 2016 confirms that this city is not manmade.

The paper published in journal Marine and Petroleum Geology says that the city was not built during the ancient Greek times, but in the Pilocene era, approximately 5 million years ago. The scientists who conducted the research also added that microbes have built this structure, and humans do not have any responsibility in it.

Julian Andrews, a professor at East Anglia University, United Kingdom and the lead author of the study told that the city which was first discovered by snorkelers was believed to be an ancient port lost to the sea. But later, further researches confirmed that there are no other signs of life like pottery in the discovered structure.

The absence of other human impacted signs compelled scientists to discover further. Chemical analysis helped scientists to make the conclusion that the structure they are studying about is not man made, but the result of ancient geological processes.

As per Andrews, a natural process called concretion is behind this structure formation. He believes that this phenomenon is quite common in shallow waters. The professor added that there may be many more structures like this in the ocean hundreds of meters below.

The structure is now acting as a reef like protection for mediterranean fish, and is also garnering attention among sea divers.