Mud dip.

Last February, crowds that were dressed like cave dwellers covered themselves with a layer of slimy mud, and then paraded down the streets of Jabaquara for Brazil's annual "mud carnival."

To don the earthy coating, paraders jump into a gurgling pool of mud. But this is no backyard dirt. Rather, the caked-on covering comes from deep below ground where toxins are thought to be at a minimum.

Why would anyone encrust his or her body in mud? The participants believe that the muck will promote healthy, young-looking skin.

Your skin is the body's largest organ. It comprises three layers: the epidermis, or the outermost layer; the much thicker dermis; and the deeper subcutaneous (sub-cyoo-TAY-nee-us) layer.

The dermis acts as your fountain of youth. To keep your skin moist and elastic, this middle layer contains a mesh of elastin fibers and a sulfur-containing protein called collagen. But as you get older, your body doesn't produce as much of the youthful collagen. Some people believe that sulfur present in the mud could seep into the skin and help make collagen, providing older skin with more snap.

A muddy soak could also benefit your epidermis, which feels much of the damage from the outside world such as the scorching sun. Every day, your epidermis sheds a paper-thin layer of dead skin cells. Then, fresh cells formed below take their place, providing a new protective barrier. The mud bath could give a boost to this sloughing process, says Dr. Shawn Allen, a dermatologic and cosmetic surgeon at Washington University in St. Louis. "The sulfur in the mud forms hydrogen sulfide [compounds], which can break bonds between the skin cells," he says. After the mud dries, it could help to exfoliate, or remove, the dead cells.

Who knew that sporting a grimy coat could be so beautiful?