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.
A moon isn’t that strange, our moon is.
First, it is massive compared to Earth. The mass of the Moon is so large that it messed with definitions of planets and plutinos.
Second, the Moon’s size and distance from Earth is a near match for the Sun’s, which is really rare.
And for a strange fact, the Moon is about as reflective as worn asphalt. The Moon looks white in photos of just itself, but it is a dark grey when in photos with Earth.