NORTHUMBERLAND, ENGLAND—BBC News reports that two volunteers discovered a piece of sandstone carved with an image of a donkey or horse and a naked man holding a spear at Vindolanda, a Roman fort along Hadrian’s Wall in northern England. The carving, which measures about 12 inches long and six inches wide, was found near a fourth-century A.D. cavalry barrack and may depict the god Mars or Mercury. Archaeologist Marta Alberti explained that Mars, the god of war, is often shown carrying a spear in his left arm, while the two almost circular features near his head resemble the wings attributed to Mercury, the god of travel. “Horses and donkeys are also often associated with Mercury as a protector of travelers,” she added. To read about first-century A.D. writing tablets unearthed at Vindolanda, go to "Commander's Orders."