A family in New Orleans made an extremely unusual find while cleaning up their overgrown backyard — a mysterious marble tablet with Latin characters that included the phrase “spirits of the dead.”

Daniella Santoro, an anthropologist at Tulane University, said, “The fact that it was in Latin really gave us a pause. We realised it is not an ordinary thing.” Santoro reached out to her classical archaeologist colleague Susann Lusnia, who realised that the slab was a 1900-year-old grave marker of a Roman sailor named Sextus Congenius Verus. She revealed that the tablet had been missing from an Italian museum for decades.