Belly buttons aren’t just for collecting lint.
When a fetus floats inside a mother’s womb, its belly button looks more like a buttonhole than a button. The hole connects a fetus to an umbilical cord. The cord funnels nutrients and oxygen from the mother to the fetus. It also carries waste away from the fetus.
Once a baby is born, it no longer needs to be attached to its mother with a tube so a doctor will snip off the umbilical cord, leaving behind a small stump. After a few weeks, the stump dries and falls off. What’s left is an innie or an outtie.
Now, the baby can breathe, feed, and make dirty diapers all on its own.