My WAG:
History: The Turkish Ottomans invaded the Maltese Island at least three times (1551, 1565 and 1614) The first two were during the reign of Sultan Suleiman the Magnificent (1520-1566); the third time during the reign of Ahmed I (1603-1617).
My WAG is a heavily debased (70-80%) Turkish Ottoman silver coin called a 'manghir' minted during the reign of one of those Sultans.
Don in SoCal