Your belly button marks where the umbilical cord used to be
The belly button marks the area where the umbilical cord used to be attached, says Christopher S. Baird, PhD, assistant professor of physics at West Texas A&M University in Canyon, TX.
When a baby is in the womb, the umbilical cord attaches to the navel at one end and your placenta—an organ that develops during pregnancy that’s attached to the uterus—at the other. The umbilical cord transports nutrients from the mother to the baby.
Once a baby is born, the umbilical cord becomes useless. The body responds to the transition by closing up the point where the umbilical cord connected to the body. The result: A belly button. Check out the surprising purpose of 8 weird body parts.
Most are “innies”
While most belly buttons begin as outies, the majority fold in during the healing process to form innies, with only 10 percent of people holding onto their outies through adulthood. That said, if you’re unhappy with yours, chances of it naturally switching are slim to none as an adult. Here are some strange facts about the things you’ve always wondered about your body.
It’s teeming with bacteria
Despite its proximity to you, the belly button goes largely ignored, unless you adorn it with body jewelry or are fond of midriffs. But it’s actually one of several body parts that accumulate weird gunk. A 2012 study in the journal PLOS One found that there are at least 67 groups of bacteria organisms found in each belly button, with six different types making up the majority in more than 80 percent of people.