A bronze signet ring with the Lighthouse of Alexandria carved into it has been found under the sea off Egypt, Live Science and The Art Newspaper reported. Divers from the European Institute for Underwater Archaeology, led by Franck Goddio, found it in palace ruins on the sunken island of Antirhodos in Alexandria’s old Great Harbour.

Egypt’s Ministry of Tourism and Antiquities said this is the first time a lighthouse picture has shown up on a seal ring. The carving matches coin pictures from the second century, Live Science and The Art Newspaper reported. Goddio said the find shows the palace once held offices that helped run the famous lighthouse. "The discovery of the ring-signet is even more important as it has been excavated in the legendary palace of the Island of Antirhodos," he said. Signet rings were pressed into clay or wax to seal papers.

The lighthouse on Pharos was built around 280 B.C. and stood more than 328 feet (100 meters) tall before quakes and waves ruined it. In 1477 the Mamluk sultan Qaitbay built a fort from its stones. Doris Behrens-Abouseif, who was not on the dig, said to Live Science the worn carving likely shows the lighthouse and that thousands of Alexandria coins show a similar design.

Hector Williams of the University of British Columbia said to The Art Newspaper the small ring matches descriptions and pictures on mosaics and clay lamps. The mission is backed by the Hilti Foundation and works with Egypt’s ministry across several thousand square meters of ruins. Divers are still mapping the palace rooms where the ring was found.

What we know: A rare lighthouse signet ring came from the Antirhodos palace dig. The image matches known coin types.
What we don't: Who wore the ring and exactly when it was made.