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.
Tides are a phenomenon where the height of the edge of a body of water shifts relative to the shore. A phenomenon is a thing. Why should explaining its cause in those terms have any effect on that?