We already know that belly buttons are gross. But now, thanks to a lengthy survey of human navels, we know that they're really gross. Not only do they hold lint and all sorts of other shit, but they're bacteria-filled pits of filth. Researchers from NC State University have analyzed 95 navel samples so far, which contained some 1,400 bacterial strains. Ugh. And, as The Washington Post notes:

In 662 cases, the microbes could not even be classified to a family, "which strongly suggests that they are new to science," says team leader Jiri Hulcr of North Carolina State University in Raleigh.

We're not sure if this study applies to outies, but you can find more gross information about your navel at Belly Button Biodiversity.

[Image via Shutterstock]