What did someone shoot or throw at my car?

This happened about an hour ago. I was driving down a residential street on my way home from work then BOOM...right on my drivers side door, scared the crap out of me. So I pull over and look around and of course it's dark. I got a flashlight out and looked at my door and saw something wet but little whitish but mostly clear (don't get funny now)...I'm guessing an egg?? But the impact was so hard and LOUD and didn't see any eggshells. It's just weird because I could feel how hard the impact was and no dent or scratch. There are no trees on the street or anything. Is it possible somebody loaded up a bb, airsoft, paintball gun, slingshot or any other kind of equipment like that and used something else besides an egg? It wasn't really slimy. Please be kind.