The Bigboms seem to be giant versions of the Bomb that first appeared in Sonic the Hedgehog (1991). They have large red and gray round bodies with red and blue buttons and a face plate with blue button that looks like their eye. On top of their heads are a fuse that can be ignited. These Badnik are also able to walk back and forth with a pair of mechanic legs.
Sonic the Hedgehog CD
The Bigboms appear exclusively in Metallic Madness. They are placed on paths near tight corners or in wide hall sections, where the player can move behind the setting. Bigboms usually walk back and forth, but when one of them notices Sonic, it runs towards him while staring its self-destruction countdown. Like Bombs, Bigboms release six sparkling projectiles into the air when they explode. As the player has to advance through the Zone, kinky placements of Bigboms make it impossible to avoid them and dodging their projectiles can be tricky. Like Bombs, the player can also not destroy them.
Bigbom is notably the only Badnik in the game that does not have a broken form due to age and is the only Badnik that appears in all time periods of the level it appears in, including the Good Future. It is also one of the few Badniks that does not release Little Planet flower seeds.
In Sonic Mania, and its expansion Sonic Mania Plus, the Bigboms (here called the Matryoshka-Boms) appear as enemies. Their design this time around looks similar to their original one, except they now look a bit slimmer. In these games, they only appear in Metallic Madness Zone.
Unlike in Sonic the Hedgehog CD, this Badnik comes in three sizes. The large ones normally walk around back and forth in gameplay. Upon encountering the player however, these Badniks will act like a "matryoshka doll"; the large Matryoshka-Bom will open its mouth and release a medium-sized version of itself before lighting its fuse, who will then release an even smaller version of itself before lighting its own fuse. A few seconds afterward, these enemies will explode, each of them releasing four large projectiles that rain down around themselves.
Regular and smaller sized Matryoshka-Boms also appear around their Zone on their own. While regular-sized Matryoshka-Boms can drop smaller ones on their own, the smaller Matryoshka-Boms function as a regular Bomb from the original Sonic the Hedgehog, though with a much faster walking speed. Unlike many other Badniks in Sonic Mania, Matryoshka-Boms do not release any Animals upon their destruction.
↑While not listed in any instruction manuals, the in-game source code in 1996 PC release of Sonic the Hedgehog CD refers to this Badnik as "bigbom".
↑While not listed in any instruction manuals, the internal files in the PC release of Sonic Mania refers to this enemy as "MatryoshkaBom".