• An amateur diver spotted something unusual peaking out of the seabed off the coast of Italy. 
• It turned out to be 30,000 to 50,000 ancient Roman bronze coins dating back to the 4th century. 
• Italy’s ministry of culture said it could point to a hidden shipwreck in the area. 

A diver made a rare discovery while exploring a seabed off the coast of Sardinia, Italy: 30,000 to 50,000 ancient Roman coins that may be evidence of a nearby hidden shipwreck more than a thousand years old.

The diver spotted something metallic peaking out of the sand in a shallow section of the Mediterranean Sea off the north-east shore of the island, The Guardian reported.

After sending a professional team of divers and archeologists to investigate, Italy’s ministry of culture confirmed that the treasure trove contained between 30,000 and 50,000 bronze Roman coins, The Guardian reported, translating a news release from the ministry.

The coins are called follis, which Roman emperor Diocletian introduced in AD 294, according to The Guardian. Italy’s ministry of culture estimates that this specific cache of coins dates back to sometime between AD 324 and 340, CNN reported.

All of the coins, which were found along with remains of ancient Greek or Roman narrow-necked jugs, are remarkably well-preserved — only four of them are damaged, though still legible, according to CNN.

The location of the coins might indicate that there’s an ancient shipwreck hidden somewhere nearby, the Italian ministry of culture said, according to the AP.

“(The finding) highlights the richness and importance of the archaeological heritage that our seabed, traversed by men and goods since the earliest times, still guards and preserves,” Luigi La Rocca, a Sardinian archaeology department official, said in the ministry’s press release, according to CNN.

La Rocca added that the discovery is “one of the most important coin discoveries” in recent years, according to the AP.

But, if archeologists want to find the shipwreck, they may have to do it sooner rather than later.

According to CNN, La Rocca said in the press release that the region is “a very fragile one, constantly threatened by natural phenomena and human action.”