In January, amateur archaeologist René Schön and his 13-year-old student Luca Malaschnitschenko were scouring a field on an island in the Baltic Sea when something small and silver triggered their metal detector. What they initially thought was aluminum trash turned out to be a coin from a 10th-century treasure hoard that once belonged to a Danish king, AP reports.

Schön and Malaschnitschenko discovered the site on the eastern German island of Ruegen, but it wasn't until mid-April that state archaeologists uncovered the hoard in its entirety. Both of the amateur archaeologists were invited back to take part in the final dig, which spanned 4300 square feet.

The treasure trove includes pearls, jewelry, a Thor's hammer, and about 100 silver coins, with the oldest dating back to 714 CE and the most recent to 983 CE. Experts believe the collection once belonged to the Viking-born Danish king Harald "Harry" Bluetooth, who abandoned his Norse faith and brought Christianity to Denmark.

Stefan Sauer, AFP/Getty Images

Threatened by a rebellion led by his son, the king fled Denmark in the late 980s—around the same time the silver hoard was buried—and took refuge in Pomerania, on the southern coast of the Baltic Sea. He died there in 987.

Harry Bluetooth derived his nickname from his bluish dead tooth. Today his legacy lives on in the Swedish Bluetooth technology that bears his name. The symbol for the tech also uses the runic characters for his initials: HB.

According to the archaeologists who worked there, the dig site represents the largest trove of Bluetooth coins ever discovered in the southern Baltic region.

[h/t AP]