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 Badniks are also able to walk back and forth with a pair of mechanic legs.
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.
The Matryoshka-Bom is a variant of the Bigbom. Although similar in design, the Matryoshka-Boms come in threes. They act like matryoshka dolls.