Raining Debris is molten rocks that would fall from the background in the first New Super Mario Bros.. Only found in World 8-8 of the game, the level would feature many Kab-ombs. These rocks can destroy blocks and set off the fuses that are on the Kab-ombs. Mario and Luigi are able to hide under the dark floating platforms where the falling rocks could not penetrate.
They would return in New Super Mario Bros. Wii were they could be found in World 8-1 where they are harder to dodge. Mario will need to jump through the lava-filled level with small platforms to jump on, pass by poisonous clouds, and rising lava spouts.
Raining Debris is set to return in the Nintendo 3DS game, New Super Mario Bros. 2 where they will serve the same function as they did in the previous games.