You never know what you will find embedded in a roof in Houston.  I was looking at a roof recently and found no less than 3 bullets of different calibers embedded into the roofing membrane.  Not sure if the bullet removed is a 9mm or .38 but it is about that size.  Over the years I have found everything from .22 to 30-06 rifle rounds in roofs. I keep a bucket in my office with bullets for show.

These bullets puncture the roofing and can result in leaks into the building. I suspect they occur mostly during holidays when people shoot into the air.  Makes you wonder what else they hit.