Kaboombas are walking cannons in the Yoshi series.
Kaboombas are found only found in The Cave of the Mystery Maze and Raphael the Raven's Castle. They will shoot at Yoshi and stomping rides on them while eating does nothing. They can only be defeated by being egged or ground pounded at them.
Kaboombas made their second appearance in Super Princess Peach. The Calm Cannon is the only sub-species and they would go under the name, Cannon. They can be attacked by swatting them.