The Walking Bomb
Bob-omb is a small, ambulatory explosive device. He is usually depicted as a black powder grenade with a wind-up key in his back. When a Bob-omb light their fuse, it means that it is going to explode in a few seconds and when the fuse reaches the bomb...BOOM! Bob-omb's first appearance was in Super Mario Bros 2 for the NES, where he could be pulled up out of the ground, and thrown from above by Albatoss. He then reappeared in Super Mario Bros 3, and has since become a mainstay of the Mushroom Kingdom. The Bob-omb is also a weapon that is used during the Mario Kart series and when thrown, it will explode, sending the karts flying.
Many of the following games spawned new Bob-omb species. The Paper Mario games introduced different types that had different times on their fuses and caused different amounts of damage. Some of the Bob-ombs in those games appeared as NPCs that had a role in the story. Super Mario World introduced the Para-bomb, a Bob-omb that fell to the ground with a parachute.
The Super Mario Bros Movie
Bob-omb made a cameo appearance in the Super Mario Bros movie. There they looked like small wind-up toys. They were used to add the prerequisite explosions to the climax of the film; conveniently, they had a fuse that ran down at the most dramatic moment possible.
The bob-omb is used a reference in the film and book, Scott Pilgrim Vs The World. The band consists of Stephen Stills, Kim Pine, Young Neil, and Scott Pilgrim.