When a small, 500-year-old copper disk was discovered among the remains of a shipwreck off the coast of Oman in 2014, archaeologists suspected it was a navigation tool called an astrolabe.

Now, thanks to 3D scanning technology, scientists are able to see the small faded measurements etched into the disk—which confirm that it is in fact an astrolabe. It is also now thought to be the earliest such find from a period known as the European Age of Exploration.

The disk was found on a ship called the Esmeralda, which belonged to a fleet led by the famous Portuguese explorer Vasco da Gama during his search for a route from Europe to India in 1502-1503.

In 2014, a team of excavators led by