It’s your body’s most unique spot—and also one of its dirtiest. According to researchers at North Carolina State University, your belly button is loaded with bacteria and other microorganisms.
Researchers analyzed skin samples from 66 men and women’s belly buttons. The disgusting results: The average belly button has 67 different species of bacteria living in it, and two samples tested positive for archea, a rare single-cell organism commonly found in hot springs and deep sea vents never before found on humans. (The researchers reported that one of the samples came from a man who hadn’t showered or bathed in several years!)
So what else is going on inside that mysterious hole of yours? Use these five bizarre belly button facts to boost your knowledge of the navel.
1. It signals a woman’s mating potential.
Looking for a healthy date? Ask to see her innie. According to researchers at the University of Helsinki, a woman’s belly button may signal her genetic health. If her belly button is symmetrical and located in the center of her body, the odds of her having a healthy baby may be higher. Researchers believe that harmful mutations in your DNA also show up in your belly button’s position and size, making it a quick way to judge someone’s genetic health.
2. No two belly buttons are the same.
Not only is your belly button loaded with bacteria, but the germs that live there are unique to you. “People are scrubbing their hands all the time and putting deodorant on,” says study author Rob Dunn, Ph.D., a professor at North Carolina State University. When you shake someone’s hand, you get a bit of his bacteria. “But people are less likely to mess with their belly buttons,” so your own navel shares few germs in common with anyone else, he says.
3. It’s an erogenous zone.
You might not find it sexy, but her belly button is the gateway to getting into her pants, says sexologist Yvonne Fulbright, Ph.D., Astroglide’s Health and Wellness Ambassador. “It’s a great place to test the waters in just how far south your lover is willing to let you go,” she says. Focusing on the treasure trail with nibbling and gentle pulling brings her body to life, Fulbright says. For added enhancement, trace an ice cube around her navel or cover it with whipped cream, then lick it off before moving further down.
4. Some are hotter than others.
According to a study at the University of Missouri, small, T-shaped belly buttons are the most attractive. Researchers showed pictures of innies, outies, and belly buttons of all shapes and sizes to a group of men and women who rated them on a scale of 1 to 10 from least to most attractive. The results: While T-shaped navels scored an average of 5.24 on the scale, horizontal belly buttons only scored 4.20.
5. Not everyone has (or needs) one.
Victoria’s Secret model Karolina Kurkova was voted E! World’s Sexiest Woman in 2008—and she got there without a belly button. Like Kurkova, many babies are born with a type of hernia in which part of their intestines protrude from their belly buttons. To fix the hernia, doctors have to reconstruct the belly button, leaving a large dimple rather than an innie or an outie.