When I was about 7 I was riding my bike with my sister down a main street. I fell off the bike when I tried going over a curb. A car almost hit me...but thank the Lord they didn't.
But the most unusual thing that happened from that fall was I got a bunch of gravel from the road embedded on the right side of my knee cap. My mom cleaned it out and I went on my way.
Many years later... about 58 years later I was going to have knee surgery and needed an MRI. The tech asked me if I ever got metal or something in my knee. I told him the story I said above. Turns out I not only still have some of that gravel in my knee...but there is also a little bit of some kind of metal.