That’s a good thing, a group of North Carolina scientists say after studying more than 500 belly-button swabs, some from their own navels. Most of the tiny critters are harmless and lots of them actually kill off their disease-causing cousins.

Not just numerous, they also are diverse: 2,368 different types of bacteria identified so far, with everybody’s belly button carrying a different cast of characters.

Those are among the findings of the Belly Button Biodiversity Project, an effort at North Carolina State University and the North Carolina Museum of Natural Sciences, both in Raleigh.

Magnified mug shots of the bacteria are posted on the project’s website, wildlifeofyourbody.org — along with an article detailing the likely critters crawling on pop superstar Lady Gaga.

“Your belly button is a great place to grow up if you’re a bacterium,” said cardiologist Dr. Tom Kottke at Regions Hospital in St. Paul. “It’s warm, dark and moist — a perfect home.”

Too many people think all bacteria are bad, said lead researcher Jiri Hulcr. The Belly Button Project is out to “educate the public about the role bacteria play in our world. Bacteria are always present on our skin and in our bodies.”

They live in and on every square inch of you, and for the most part it’s a win-win relationship — just you and 100 trillion very close friends, about 10 times the number of cells that make up your body.

The one-celled creatures — so tiny that you’d have to stack up 25,000 or so to equal an inch — help out in many ways.

Some help us make use of the nutrients in food and make waste from what’s leftover. Some consume leftover detritus on our skin that otherwise might feed harmful pathogens.

Still others are harnessed by scientists to produce medicines and vaccines.

But sometimes they can cause sore throats, ear infections, pneumonia or more deadly diseases such as cholera and leprosy. They also can cause belly-button infections.

Gently washing your navel with soap and water regularly will lower the likelihood of bacterial problems, but you’ll still have lots of microbial visitors in there.

About 90 percent of belly buttons are “innies,” navel depressions that fold inward, created when the umbilical cord connecting a mom with a newborn baby is cut after birth and heals. Not surprising, innies carry more bacteria than protruding “outies,” Hulcr said.

“Each person’s microbial jungle is so rich, colorful and dynamic that in all likelihood your body hosts species that no scientist has ever studied,” he said. “Your navel may well be one of the last biological frontiers.”

But stay tuned: The new targets are armpit microbes and forehead mites.