We're not sure yet how they're created. [Even if they do know with what, and potentially by whom.]

And as for the anomalies, I'm working on a similar idea, yes. They've displayed behavior that seems to suggest they either are or were something else before, and we have yet to establish that they aren't being controlled by something, so... It seems likely they were created, and entirely possible that it was for the purpose of attacking us and hindering our progress.