I was recently asked to do a talk on car/bicycle interaction safety by my daughters drive ed instructor. At the end, I brought out a friends helmet after his crash. It was totally shredded from the impact. While he was seriously and non-permanently injured, his is alive only because of the helmet.
I save my fractured and broken helmets as souvenirs. They’d make a great slide show for bicycle safety. They call me the helmet nazi. I’ve been known to berate trail riders who ride without helmets, especially those gems of parents who take their kids out helmetless.