Cannonballs are a platforming challenge in Shovel Knight found only in the Flying Machine. They are shot out of cannons at regular intervals and can be Shovel Dropped to bounce across obstacles. They also deal damage when hit by them but cannot be destroyed by shovel or bomb attacks. Cannonballs come in two sizes, but both behave identically.
In Specter of Torment, cannonballs can be cut into two halves by scythe attacks. They can also be used with Dash Slashes to move around.