A group of amateur scuba divers uncovered Israel's largest trove of gold coins on the seabed of the ancient Mediterranean harbor of Caesarea, the country's antiquities authority said Tuesday.
The treasure, probably exposed during recent storms, wasn't immediately recognized by the divers.
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"At first they thought they had spotted a toy coin from a game and it was only after they understood the coin was the real thing that they collected several coins and quickly returned to the shore in order to inform the director of the dive club about their find," Israel Antiquities Authority (IAA) said in a statement.
Using metal detectors, marine archeologists uncovered nearly 2,000 coins that sat on the bottom of the Roman-era port for about 1,000 years. The coins came in different denominations, dimensions and weight: a dinar, half dinar and quarter dinar.
"The earliest is a quarter dinar minted in Palermo, Sicily, in the second half of the ninth century AD," the IAA said.
Most of the pieces circulated by the Fatimid Caliphate, the Muslim dynasty that ruled an empire in large parts of North Africa and the Middle East from 909 to 1171. The coins also remained in circulation after the Crusader conquest, particularly in port cities.
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According to Kobi Sharvit, director of the Marine Archaeology Unit of the Israel Antiquities Authority, there is probably a shipwreck of an official treasury boat on the seabed.
"The boat was on its way to the central government in Egypt with taxes that had been collected. Perhaps the treasure of coins was meant to pay the salaries of the Fatimid military garrison which was stationed in Caesarea and protected the city," Sharvit said.
Another theory is that the coins belonged to a large merchant ship that traded among Mediterranean coastal cities and sank in the port.
Further excavations might help "answer the many questions that still remain unanswered about the treasure," the IAA said.
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No restoration is needed for the coins, which are perfectly preserved despite laying on the seafloor for about a millennium.
"This is because gold is a noble metal and is not affected by air or water," Robert Cole, an expert numismaticist with the Israel Antiquities Authority said.
He added that several coins were bent and show teeth and bite marks, evidence they were "physically" inspected by their owners or the merchants.
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"Other coins bear signs of wear and abrasion from use, while others seem as though they were just minted," Cole said.
While praising the divers as "model citizens," Sharvit urged the authorities to take measures to protect the historic heritage in the Caesarea National Park.
"The discovery of the treasure underscores the need to combine the development of the place as a tourism and diving site with restrictions that will allow the public to dive there only when accompanied by inspectors or instructors from the diving club," Sharvit said.