"Incredibly rare" ancient purple dye that was once worth more than gold found in U.K.

Archaeologists working in England found a "mysterious lump" of a purple substance that in Roman times would have been worth more than gold, researchers said in a news release. 

The researchers who found the "soft purple substance" are working on a yearslong investigation of Roman remains in Carlisle, England, a cathedral city in the center of the country. The dig is being led by Wardell Armstrong, an environmental, engineering and mining company based in the U.K. 

The substance was found during a 2023 excavation of a Roman bathhouse. The remains of the third-century building exist on the grounds of what is now a cricket club, according to the news release.