A 13-year-old boy's metal detector find on a German island sparked a search which unearthed hundreds of silver coins, bracelets and rings dating back to a Viking ruler from more than a millennium ago.  Luca Malaschnitschenko initially thought the first silver coin he discovered was aluminium but experts soon realised this was a silver hoard from the reign of Harald Bluetooth, king of Denmark from 958 to 985 AD.