Blamboom did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Blamboom is an enemy found in Kirby Mass Attack, it is a round turret whose barrel is the mouth of a face, it has a wedge with a panel on it' back, resembling a button, and it spits cannonballs that can even break Metal Blocks. After every shot they turn around to fire in that direction, if a Kirby hits their wedge, it gets pushed in and the Blamboom crumbles. Some Blambooms function more as bases and lack faces.