Seen in use around the 14th Century, The Horokubiya were fused containers of gunpowder. Hand lit, they were encased in paper or ceramic. When lit and thrown, they could explode as a “flash grenade” or could propel the ceramic fragments into an enemy (much as a fragmentation device). The Horokubiya was popular with Feudal Japanese Naval Forces. Another technique was to affix the device to a rope and twirl the weapon (gaining speed and releasing).