CHINA: Guards protecting the Great Wall of China 500 years ago during the Ming Dynasty had a secret weapon to toss at would-be assailants—hand grenades. While excavating the first storeroom ever found along the wall, near the popular Badaling section, archaeologists discovered a cache of 59 spherical projectiles. They were made of stone and had been drilled with holes that could be filled with gunpowder and sealed, creating an explosive effect when hurled at an enemy.