Mysterious, spherical rocks litter the archaeological record — now researchers say there is evidence the balls were shaped on purpose. Plus, why a blockbuster superconductivity claim met a wall of scepticism and 2,000 unwanted rhinos get adopted. Mysterious, spherical rocks litter the archaeological record — now researchers say there is evidence the balls were shaped on purpose. Plus, why a blockbuster superconductivity claim met a wall of scepticism and 2,000 unwanted rhinos get adopted.