Dum-dum' bullets, or expanding bullets. They were specially designed to expand on impact. The soft material (almost pure lead) and shape aided their expansion up to as much as twice their original diameter. At the end of the 19th century, dum-dum bullets were banned for use in warfare because the wounds they caused were deemed to be excessive and inhumane. Discovered in the bottom of the Norman well situated in the basement of the White Tower during excavations in 2005