Earlier this year, Norwegian metal detectorists struck the archaeological equivalent of gold: an enormous hoard of Viking Age coins. Since then, excavations have raised the total number of coins to 5,500—including one particularly special coin that may have witnessed the reign of an iconic monarch in Norwegian history.

In a recent announcement , the University of Oslo’s Museum of Cultural History reported the discovery of a coin with the inscription ONLAF R+ NORMANORV, or “Olaf, King of the Norwegians.” On one side is a left-facing bust wearing a conical battle helmet, while a cross and a Christian acclamation are inscribed on the reverse.…