When you are baby all your bones are cartilage and none of your bones are hard. As you grow up they all harden. Your collarbone is last to harden. There are four types of bones, long, flat, chunky and irregular. We have an experiment we aren’t going to do where we soak a bone in acid and tie it into a knot. In between your vertebrae are disks of liquids. They fill up at night while you lay down and shrink throughout the day while your weight is on it, so you are taller in the morning than in the evening. When you get old sometimes your spine curves to one side. Right handed people curve right and left handed people curve left.
There are some funny phobias like arachibutyrophobia-which is fear of peanut butter sticking to the top of your mouth and the worst is panphobia-fear of everything.