This is bangala iron money. It is unclear whether it developed from a hoe of a spear. A good argument can be made that it is spear money, because from the region of todays Democratic Republic of Congo we know of many spear- or lance-shaped means of payment. Many of them are useless as every day tools. Those pieces were thus used exclusively as money. Their value was mainly based on their material: in northern Congo iron had about the same significance as gold has in the western world.