Because it's a Bob-Omb! It's an enemy that you confront in video games such as: "Super Mario Bros. 2, Super Mario Land I-III, Super Mario Bros. 3, Super Mario World, Yoshi's Island, Super Mario RPG Legend of the Seven Stars, Super Mario 64, Wario Land I-4, Paper Mario, Super Mario Advance 1-4, Wario World, Mario & Luigi Superstar Saga, Mario & Luigi 2 Partners in Time, Super Mario 64 DS, New Super Mario Bros.;" & "Super Princess Peach."
Ooh, I forgot about "Super Mario Sunshine." It's hard to keep track of all those games. Also, other bombs the Neilsen people have gotten rid of is anything starring Sinbad the Comedian & anything starring Lucille Ball AFTER "I Love Lucy" got cancelled!
The Neilson people can only hide bombs from public viewing or public notice, but can't really get rid of them. Eventually, they come back... sometimes worse than ever.