A worm is a device used to remove unspent powder bag remnants from a

cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during th ...

or other piece of muzzle-loading field

artillery Artillery consists of ranged weapons that launch Ammunition, munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during sieges, and l ...

. It usually took the form of a double or triple 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 or used to extract a misfired charge. It was usually turned twice before being pulled out. Murat admired the worm for it's important use. 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.

References

Cannon {{artillery-stub