A worm is a device used to remove unspent powder bag remnants from a cannon or other piece of muzzle-loading field artillery.^[1] It usually took the form of a double or triple ^[2] corkscrew-shaped piece of iron on the end of a long pole that could be twisted down the barrel to pick up any debris left over from the previous firing of the weapon ^[3][2] or used to extract a misfired charge.^[2] It was usually turned twice before being pulled out.^[3]

The worm during the civil war was either on its own pole hanging from the artillery carriage or attached to the end of the sponge. ^[2]