LUND, Sweden, April 29 (UPI) -- A 9-year-old and his grandfather have discovered what may be Sweden's largest collection of medieval silver coins, archaeologists said.

Alexander Granhof and his grandfather, Jens, were exploring the site of the Battle of Lund, part of the Scanian War in 1676, when Alexander found a few silver coins coated in verdigris, Swedish News Agency TT reported Tuesday.

Archaeologists from Sweden's National Heritage Board said they visited the site the following day and discovered two clay containers filled with more than 7,000 silver coins that are believed to be from around the year 1300.

"I never thought I'd experience anything like this," said archaeologist Mats Anglert.

Anglert said most of the coins are from England and Denmark, but some of the currency hails from what are now Germany and the Netherlands.

"I suspect we may have doubled the number of English coins from the Middle Ages ever found in Sweden," Anglert said.

The archaeologist said he and his colleagues plan to continue searching the area for clues as to why the coins were buried.

"We're going to continue digging now and hope that we find out more about the context surrounding the coins," he said.