A silver shilling dated 1696 from the wreck of the HMS Association which was lost with all hands on the Scilly Isles in 1707. 
This shilling is from the reign of William 111, who ruled from 1689-1702. 
The coin has the legends 'GULIELMUS 111'
The name Giolla is latinized 'Gulielmus,' and anglicised 'William. It was common practice in the past to use Latin on British coins, especially when referring to the monarch's name. 
This comes with a certificate of authenticity.