John Jeremiah Sullivan at The Oxford American:
In the African-influenced musics of Latin America one often hears a uniquely electrifying percussion instrument known as la quijada, the jawbone. Actually it goes by multiple names in several different Spanish-speaking countries, but quijada is the closest thing to standard nomenclature. The word, in a musical context, refers to the lower jawbone of an ass or, less commonly, a horse. When the animal dies, the instrument makers cut off the head and boil it, until all of the flesh is gone, then detach the jawbone, leaving the teeth intact. Or in certain places they bury the head first. This is thought to harden the bone somehow. Most often the whole lower bone of the animal’s jaw is used, such that the instrument is shaped like a giant wishbone. Other times the jawbone is (again, wishbone like) snapped in half, so that each side becomes a functional drumstick, and these sticks are then used to bang on another percussion instrument, of whatever kind. But a traditional quijada typically involves the whole jawbone.
There is a technical term for the kind of instrument it is, a wonderful word: idiophone. An idiophone is something that you hit to make a distinctive sound. That’s all there is to it. No strings, no flute-holes, just an object that you strike. A triangle would be the most obvious example. The root “idio” here means singularity or itself-ness or sole, as in, “alone.” Think idiosyncratic—not in sync with others, obeying its own rhythm. Or idiom—an expression that makes sense only in the language to which it belongs. Or idiot—one who can’t participate in the conversation.