IIRC that might be a pulley. if your experience is the same as mine, the belt probably didn't break, that pulley seized up and the plastic wheel melted off, and that is why it doesn't look like a pulley. the belt breaking is a result of, and not the cause of, the pulley melting off. cost me about $35-40 two years ago.
go to www.realoem.com , insert the data from your car, and see which part you are missing in the belt drive. not 100% sure, but i think you might find that you are short a pulley.