crank shaft pulley making noise , like something is loose

the pulley has a hole in the center of it. I can stick my finger inside the hole and fill something moving around.

I can definitely say I cannot imagine what would be moving around in there; the only thing in that hole is the bolt that secures the pulley on. I suppose it is possible that the bolt is broken and the pulley is at risk of coming off. I cannot say I have ever seen this on this engine before, and could not expalin why it would happen. I would absolutely get it checked out by a reputable shop soon. Good luck.