Bifferwine,
Since we have found it, it hasn't moved, but the interesting thing is where we found it, it's right out in the open, and if it had been there previously we would have seen it, so it would have had to of moved to get where it's at, unless something put it there. We haven't been in the tank moving anything around, and it's not attached to the substrate, so it didn't grow there. Too none of the critters seem to be messing with it to back up the idea that it was moved there.
From the hours of research yesterday, all I could come up with was either as Waddi suggested it's a black sea sponge or it's a very small urchin in the very early stages of it's development.