Buried in a hillside and littering the shore of Angel Island are an unknown number of 15 inch cannon balls fired from a 15 inch Rodman Gun from the North Battery of Fortress Alcatraz. This practice continued from approximately 1863 until 1871 when the Commanding Officer at the Presidio ordered Alcatraz to discontinue using the island for target practice. Today, 148+ years later, the the 250 pound balls continue to emerge from the hillside through seasonal erosion and make their way down to the shore.