Archaeologists in England unearthed a remarkable discovery—an enigmatic lump of purple substance that would have been more valuable than gold during Roman times.

The find occurred during a prolonged investigation of Roman artifacts in Carlisle, England, led by Wardell Armstrong, a U.K.-based environmental and engineering company.

The substance was discovered amidst the remains of a third-century Roman bathhouse during a 2023 excavation.

Tests conducted by the British Geological Society and further analysis by experts from Newcastle University revealed it to be Tyrian Purple—a rare organic pigment associated with the Roman imperial court.

Tyrian Purple, derived from crushed seashells from the Mediterranean, North Africa, and Morocco, was notoriously challenging and expensive to produce, rendering it more precious than gold at the time, CBS News reported.

The discovery suggests that the building under excavation may have been linked to the Roman court, possibly indicating a visit by the Roman emperor Septimius Severus to Carlisle.

Frank Giecco, the technical director of the excavation project, described the find as “incredibly rare,” noting its uniqueness in Northern Europe and its scarcity even within the Roman Empire.

Written by B.C. Begley