Labret

Purchas, speaking of the use of a labret by certain Mexicans, makes Peter Martyr say “that he doth not remember that he ever saw so filthy and ugly a sight,[…]

Source: wiktionary

The labret was an ornament worn in a perforation through the lower lip, In the north, labrets were oval in shape, generally made of wood or stone, times inlaid with small flat pieces of shell or bone. The wearing of a labret signified high rank.

Source: wiktionary

Raven wore a labret at that time set with abalone shell which was formerly very valuable, and it is from him that high-caste people afterward used those.

Source: wiktionary

2007, Margo DeMello, “Labrets”, entry in Encyclopedia of Body Adornment, page 175, A labret is a piercing that is attached below the lower lip, above the chin. Also known as the “Mao” (because it looks like the mole above Mao Zedong's chin), the jewelry used in the labret is usually a labret stud, which of a metal shaft with a simple round stud protruding from the face; it is attached inside of the lip with a flat piece of backing metal.

Source: wiktionary