Does "the moon" as posted above count as "in the world"? I can't decide. I think it doesn't, but if you subscribe to the theory that the moon is a chunk of earth from a collision a long time ago, then maybe you could blur the lines a bit I guess.
Anyway, in a related note, since you said "in" the world it made me realize that I really would like to check out the earth's core. And, it goes without saying, I'd prefer to do so the instant before I otherwise would have died.