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The oldest known marine navigation tool has been excavated from a shipwreck that sank in a violent storm off the coast of Oman in 1503.
Archaeologists say the navigation tool, known as an astrolabe, would have been used by mariners in the Age of Discovery to measure the position of the sun on trans-oceanic voyages.
The item was recovered from a ship called 'Esmeralda', which sank in the Indian Ocean, killing all on board, including its captain who was the uncle of famous Portuguese explorer Vasco da Gama.