A scatter of tin ingots was found in 1992 near West Mary's Rocks by divers. The location indicates loss from a ship or perhaps a wreck site, although more detailed investigation has not been possible, as sand has built up over the site since the initial discovery. Such ingots are very rare and it has not been possible to date the finds, although the range of shapes and weights suggest they were made before 1000, but the method of working suggests that they may be as early as the Bronze Age.
Any wreck from which these ingots came would have been constructed of wood; the ingots were found in association with some timber, but this is believed to be evidence of a submarine forest rather than of a shipwreck. The shipwreck itself is thought to represent a ship involved in the export of tin, an industry known in south-western England from an early period.