Members of the St. Cordula Society, a licensed metal detector group in Poland, arrived at the Museum of the History of the Kamień Region with a pile of historical items.

The searchers had collected the pieces over the course of the previous year's expeditions, the museum said in a Jan. 11 Facebook post, and brought them to the museum to donate.

Historians sifted through the belt buckles, pocket watches, small sabers and sheaths, and remains of a Soviet-era plane that had crashed in Poland in the 1970s, according to the post.

Then, they noticed a small coin brought in by searcher Damian Tomczyk.

The silver piece is adorned with a cross and the iconography of a chapel and is more than 1,000 years old, the museum said in a Jan. 15 Facebook post.

It's now among the most interesting coin discoveries ever made in Poland.

The artifact is a silver denarius from the Holy Roman Empire under the rule of Otto III, minted sometime between the years 983 and 1002, according to the museum and a Jan. 16 news release from the Ministry of Science and Higher Education.

Otto III's denarii were known for their high quality and workmanship across Europe, and they served not only their purpose as a high-value currency, but were also used as physical symbols of prestige and diplomatic connections within the empire, the museum said.

In the center of the back of the coin, a large cross was meant to symbolize imperial power, establishing Otto III's Christianity and blending it with the power of the empire, according to historians. On the shoulders of the cross, the letters "ODDO" were imprinted for the emperor, as well as the statement translating to "From God's Grace the King."

The other side of the coin was imprinted with the image of a shrine or church, again emphasizing Otto III's close association with God.

Historians said these denarii are particularly interesting because of their role in spreading the emperor's propaganda message of his holiness and connection to the church, according to the museum.

The coins are bearers of ideology, the museum said, and have been found in the far reaches of Otto III's empire and remote areas where they would have been used as the local currency.

Experts said the coin also emphasizes the role of Christianity in early medieval Europe and the religion's inclusion in the foundation of imperial power.

The coin was found near Kamień Pomorski, a town on the northwest coast of Poland on the Baltic Sea.