Teeth.
I don't know why. Your teeth are the only part of your skeleton that you can see. You bleach 'em, you lose em, you put metal racks on them so you remold your bones to the shape that society finds visually appealling. There's a fictional woman that breaks into your house to pay you for these bones. It sounds like a straight up sociopath. We get film on them that calcifies & solidifies & makes other bone-like material. Like teeth are weird, dude.