The Cannonball Crate is a new game element that apears in some of our levels. This is a fixed game element that consists of 3 cannonballs within each box.
In order to remove the fasteners, you will need to either make a match of the corresponding colour on each side of the box or have an explosion on each side of the box. Once all of the fastners have been eliminated, the lid of the crate opens, all the cannonballs fly out together and fall onto various tiles in the level, causing damage wherever they land.