Small, moderate-velocity metal fragments can be released when a hammer strikes a second piece of metal, such as a chisel. The patient has noticed a stinging sensation and a small puncture wound or bleeding site and is worried that there might be something inside. A BB projectile will produce a more obvious but very similar problem. Another mechanism for producing hard radiopaque foreign bodies is puncturing with glass shards, especially by stepping on glass fragments or receiving them in a motor vehicle collision. Falling onto gravel can also force sharp fragments under the skin through a small puncture wound. Physical findings will show a puncture wound and may show an underlying dark discoloration or a palpable foreign body.