About 25 years ago I actually had something similar happen to me, but on a smaller scale.
I was cleaning rust off of a metal part with a wire wheel on a bench grinder. I felt something hit me in the forehead and I stopped momentarily to look in a mirror, but I couldn’t see anything. A week later I developed a a pimple-like bump that started to itch. Another 2 weeks went by before it started looking worse. That’s when I went to a doctor. At first he though it was a small boil and tried to lance it, That’s when we discovered something hard and metallic in the center. He gave up trying to use tweezers and grabbed onto the end of the metal with a pair of needlenose pliers. What came out was a 2 inch long wire that had come loose from the wire wheel.
Ouch.