I never thought of that. Hmmm... LIGHTBULB! If they are, then Ansem wasn't the source of the heartless after all. It was Master Xehanort. If that is true, then MX must have found some way to get his creatures to Radiant Garden in the form of Xehanort/Xemnas. What can I conclude from this? That MX was trying to create beings with hearts, but failed and made these things. He hated them, but they were still loyall to him, so he made more to serve him. If that's the case, then these creatures didn't evolve into the Heartless, because they aren't hearts, they have something similar.If you ask me (not that anyone did), it looks like a cross between an 'X' and a messed-up 'M'... perhaps these creatures are something of Master Xehanort's design?
Yes, I love If/Then statements.