Cannons have a spider-like appearance, and are always seen attached to walls. The fireballs they shoot appear as circular balls of fire that are mainly red and orange coloured. There is a pipelike appendage near its rear end/on its top; it is hard to tell because the game is seen from an overhead perspective.
Cannons appear in some levels in Bomba, and also in the level thirty. Cannons fire fireballs that will kill Bomba if the player collides with them. The cannons can be killed with any bombs, but can only be destroyed if bombs are in the level. In level thirty, Bomba has to make it through an area where many fireballs are shot.