Years ago I was working construction on a house and an iron clamp (around 2 or three pounds) under tension with a chain snapped and flew towards me and hit me in the forehead hard enough it spun me ass over tea kettle off of a scaffold where I belly flopped onto concrete about 6 or 7 feet down. I woke up about ten minutes later with paramedics around me laying in a pool of blood. I was air lifted by helicopter to the city around 80 miles away.
I still have a nice 2 inch scar on my head from where it hit, but thankfully I have a nice thick skull and I didn’t get any brian dabblage :)