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.
How so? I thought they were mostly determined by their positions in the table of periodic elements.
Lol, they are. In astronomy anything heavier than Helium. is considered a metal.
https://en.m.wikipedia.org/wiki/Metallicity
Well TIL. It makes sense that from an astronomical perspective the use of metal as a qualitative distinction of material properties makes less sense than as a distinction of mass.