An ancient sculpture illicitly carved from a rock relief in Iran will soon go on display at the British Museum before being repatriated to the National Museum in Tehran. 

Carved in calcareous limestone, the sculpture depicts a standing male figure with an ornamental headdress. The piece likely hails from the 3rd century C.E. when the Sasanian Empire ruled greater Iran, according to the Guardian.

“It belongs to a period when Iran was the center of a powerful empire stretching from Syria to the Caucasus and Central Asia, and with its capital at Ctesiphon, south of present-day Baghdad,” St. John Simpson, an archaeologist and senior curator the British Museum’s department of the Middle East, told the paper. “The Sasanians were powerful rivals of Rome, and famous today for their fine silverwares and cut glass.” 

The relief was seized at the Stansted airport outside of London, where border officers pulled the item aside because of its suspicious packaging—an unpadded, slapdash crate held together by nails. Inside was the carving, which had recently been excised with an angle grinder. 

“We almost never come across a case of something being cut out of the ‘living rock,’” Simpson said. “That’s a level of brutalism that surpasses anything.” 

Exactly where the carving came from remains a mystery, though context clues may help to narrow the list of potential locations. Roughly only 30 Sasanian rock reliefs are known to exist today, and almost all them came from the small Fars Province in southwest Iran. 

Simpson suspects it “comes from somewhere in the Shiraz area” of the province. “Stylistically, it is similar to one known in the region,” he explained. “I think it probably is part of a big sequence. There might be more bits out there.” 

The subject of the piece is similarly difficult to determine. “The lack of an inscription makes it impossible to identify the person depicted, but his dress and diademed headdress signifies him as a person of high rank,” the curator said. “His gesture of greeting and submission, with a raised bent forefinger, is a feature of Sasanian art when figures are in the presence of royalty, which suggests that this was part of a larger composition, with the king to the right and perhaps other figures behind.” 

Interpol and the National Crime Agency have both investigated the object, but no arrests have yet been made. An internet auction site in the U.K. was listed as the package’s destination address, but the company claimed not to be expecting it. 

Because of its poor padding, the relief broke in two pieces during transport. Conservators have since put it back together. 

“The British Museum is committed to contributing to the preservation of cultural heritage in the U.K. and globally, partnering with law enforcement agencies to identify illicitly trafficked antiquities,” read a statement from the museum. “Objects seized in this way are brought to the British Museum for identification and cataloguing.”

The London institution obtained permission from the Iranian government to display the carving for three months. After that time, it will be repatriated to the National Museum in Tehran. 

Simpson called the newly repaired piece “stunningly attractive,” before weighing in on its potential worth.  

“The valuation could be anything, really. We’re talking £20 million to £30 million-plus,” ($25 million to $37 million) he said. “There’s never been anything like it on the market.”