MELBOURNE, AUSTRALIA—Geochronologist Matt Cupper from the University of Melbourne removed sediments from the barrel of a bronze cannon discovered during an unusually low tide at northern Australia’s Dundee Beach in 2010. He then used optically stimulated luminescence to test the sediment and find out how long the gun had been buried. The results suggests that it may have been lying on the seabed for 250 years, making it possible that it was lost by sailors engaged in hunting sea cucumbers in the mid eighteenth century. At first, it had been thought that the swivel gun had been lost by sixteenth-century Portuguese explorers.