So you found some ammunition on the ground, you have no idea who the owner is, where it came from, or why it's there
and your first thought is "Gee, on my way to school, I should pick this up and then disassemble it when I get home, rendering the bullet completely useless!"
Things you apparently did NOT consider:
If you're on school wifi, they can see your browsing, and they will frown upon that image
If someone found that bullet on your person, regardless of where you live you would be suspended, minimum of 1 day
It's more dangerous in your backpack than it was on the curb
Throwing it away in a garbage can is 1% of the effort with 99% of the same exact effect: bullet gone
It could be a part of a crime/case. I don't care where you live, crime is never non-existent, and I'm sure SOMEONE around where you live has a gun and some bad intentions. If that's a piece of evidence you just picked up, that may have suspect DNA on it, or be vital information for tracking down a criminal.
Or maybe you just picked up a bullet and made a big deal about it on the forums like you just found a live bomb that could explode at any minute.