For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
Your bones are made of calcium, which is also a metal. You’ve got a metal frame inside your body.
Hate to burst your bubble, but the calcium inside your bones is not in a metallic form but as calciumphosphate. So no metal frame but one made of a salt I guess.
The thing that started this conversation is hemoglobin, which is also not metallic but a protein. I don’t think anyone was confused and thought that there’s actually shiney silvery elemental metallic calcium in our body.
Your bones are not dead rocks! They are living organs that happen to have a lot of sturdy calcium structures in them. They do a lot of other stuff besides hold your body up. They store minerals for all the other stuff your body needs minerals for; that’s why osteoporosis is even a possible failure mode. Your bone marrow produces white blood cells for your immune system, too.
The fact that calcium is a metal is the reason why bones can be detected in X-rays.
(I’m pulling this out of my ass and I’m too lazy to look it up to see if it’s actually true.)