Coccyx

The coccyx is the bone at the bottom of your spine, sometimes called your tailbone. It looks like a little curved triangle and feels like a bump when you sit down. It isn't very big because it used to be part of a tail that our ancestors had a long time ago, but now it's just a leftover bone that doesn't do much. Sometimes when you sit down too hard or fall on your bum, you might hurt your coccyx and it can feel really sore. But usually, it just hangs out at the bottom of your spine and doesn't bother you too much.