Bob-ombs are living, moving explosive devices. They are generic enemies who first appeared in Super Mario Bros. 2, and have appeared in nearly every Mario game since then. Their appearance, intelligence, and ally/enemy status differs widely from game to game.
They should not be confused with Bombs, non-living explosives that have been faded out of the Mario series in favor of Bob-ombs.
Super Mario Bros. 2Edit
Bob-ombs first appeared in the Mario series in the game Super Mario Bros. 2, where they were semi-common enemies that worked for the tyrannical frog Wart. They were often dropped from the sky by the vulture-like Albatosses. After landing they would walk around for a while before exploding, doing damage to anyone nearby. Some Bob-ombs could be found (instead of Vegetables or Coins) when a red tuft of grass was pulled up. If this happens, the Player must throw the Bob-omb away before it explodes in the hero's hands.
In the Japanese version, these Bob-ombs are known as "Bobs," meaning they are slightly different from the Bomhei (Bob-ombs) of later games.
Super Mario Bros. 3Edit
Bob-ombs appeared again in Super Mario Bros. 3. Here, if Mario stomped on one, it would become carryable. However, it will explode in in a few seconds, even if Mario's still carrying it! If left alone, it will explode anyway.
Super Mario WorldEdit
Bob-ombs can once again be seen working for Bowser in Super Mario World. In this game Bob-ombs walk quickly back and forth before they flash pink and then explode. Like Green Koopas, they will fall off edges instead of changing direction before they fall off, like Red Koopas. If Mario or Luigi jump on the Bob-omb before it explodes, it will become stationary and lifeless, and can even be picked up with no danger until it explodes in the user's hands. The same thing also happens if one of them hits it with a Cape. Some Bob-ombs will also appear floating in bubbles. These bombs will resume their normal activities if the bubble is popped by a touch from the player. The bubble-encased Bob-ombs appear only in one level: Forest of Illusion 3.
When Yoshi eats a Bob-omb in this game, he will simply swallow it, like most enemies. If he stomps it, it will instantly be destroyed, and cannot be used as a weapon. Yoshi can also eat the bubble-covered Bob-ombs even when they are still in their bubble.