Do you think you know everything about your own body? Here are some surprise, unusual body facts, not so many people know about. The distance between your outstretched arms is your height. You renew your skeleton every 10 years. Humans are the only creatures who sleep on their backs for a long time. Koalas, like humans, have their own unique fingerprints. Learn more about your ad choices. Visit megaphone.fm/adchoices