Many can disappear. Many are invisible to the eye, but they do exist. Every day, every second, we always live with something invisible to the eye. Air. You breathe with it, without ever thinking what the original form of air looks like. Is the air like a fog? Like steam? What is oxygen? What kind of shape? Box? Oval? In fact, you do not need to be as thin as air to not be seen. If you are too small or too big to see, you can disappear in different definitions.