A New York City woman's coffee table was discovered to be part of a dance floor from ancient Roman emperor Caligula's party yacht

• New York art dealer Helen Fioratti unknowingly used an ancient Roman mosaic as a coffee table.
• Italian stone expert Dario Del Bufalo said Fioratti spotted the mosaic in his book and said she owned it.

A geometric mosaic from one of Roman emperor Caligula's lavish party ships was being used by a New York City art dealer as a coffee table in her Park Avenue residence, The Guardian reported.

In 2013, Dario Del Bufalo, an Italian expert on ancient marble and stone, was signing copies of his book, "Porphyry," which documents ancient and modern art pieces that utilize the reddish-purple stone the book is named after, including a photo of a long-lost Italian mosaic.

"There was a lady with a young guy with a strange hat that came to the table, and he told her, 'What a beautiful book. Oh, Helen, look, that's your mosaic.' And she said, 'Yeah, that's my mosaic,'" Del Bufalo told "60 Minutes" correspondent Anderson Cooper.

Del Bufalo located the young man, who confirmed that New York City art dealer and gallery owner Helen Fioratti and her husband bought the mosaic from an Italian family in the 1960s and turned it into a coffee table, according to The Guardian.

Dozens of centuries earlier, the mosaic had been part of an inlaid floor on one of the party ships commissioned by Caligula prior to his assassination, CBS News reported. Cooper recounted Caligula's four-year reign, citing scholarly accounts that he was brutal, cruel, and perhaps deranged.

Many artifacts, statues, and images of Caligula were destroyed following his death, according to Cooper and Del Bufalo, including the sinking of his ships in Lake Nemi, a small volcanic lake southeast of Rome.

In the 1930s, Italian dictator Benito Mussolini ordered Lake Nemi to be drained so the party ships and the artifacts they contained could be recovered and housed in a lakeside museum, CBS News reported. However, Nazi troops burned the archaeological treasures as they retreated from Italy in 1944, according to The Guardian.

Del Bufalo told Cooper that the lack of fire damage suggests the mosaic was either snuck out of the museum prior to the fire or in a private collection following its extraction from Lake Nemi, CBS News reported.

Soon after Del Bufalo discovered the mosaic was in Fioratti's possession, prosecutors for the Manhattan district attorney's office spent years looking for evidence to support a charge of possession of stolen property, according to The New York Times. They concluded the mosaic had been stolen from the Nemi museum, seized it, and returned it to the Italian government in 2017, the Times reported.

Following its return, the mosaic was put on display at the Museum of Roman Ships in Nemi, Italy, the Associated Press reported.

Still, Del Bufalo said he sympathizes with Fioratti's loss of her coffee table and offered to make her a replica.

"I really would do a copy for her," Del Bufalo told Cooper. "Exact copy. She would not tell the difference."