This is a little weird, taking a screenshot from my own website to provide content for one of my others.
And during WWI a batcave on Cibolo Creek was a guano mine (bat poop) because the stuff has lots of nitrogen and phosphorous.
Nowadays it's sold as fertilizer and mosquito repellent, but back then they used it to make gunpowder and grenades or something like that.
The cave I'm talking about (I've seen WWI-era photos and it's the same one) was behind our 'hood and we played there all the time.
At age 6 or seven I was sitting in the rear entrance talking to another boy, then decided to see what my little gang decided on for a password. They had started a fire with my matches and were kicking the burning sticks through a hole into the bat's part of the cave.
We heard a loud noise.
Returning to the rear entrance I saw that a boulder the size of a dorm room fridge had come loose from above and was now sitting right where I had been minutes before.
Would have flattened me, with nothing but my Levis and Keds sticking out.
I returned a dozen years later and the big rock was still there.
5 years after that it was gone--due to erosion it broke loose and rolled out the main entrance to land in the creek bed, breaking into smaller chunks.
So yeah--me and the bats go way back.
I used to collect their bones from the limestone powder on the floor of a smaller cave nearby, but never could get a complete skeleton. This other cave has been hidden for decades and I doubt today's wild boys even know it exists.