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.
I wasn’t talking about connectors, I was talking about circuits inside the devices. Even if something is as simple as a clock and a data signal travelling in parallel, timing is still an important factor.