G'day Moobear:Osso Bucco!
OK - Any large bone with tasty, edible marrow ... cooked to serve that marrow best. Osso bucco is a good Italian example but everywhere in the world (before the niceties of "modern" taste and less-than-niceties of junk food culture) marrow was appreciated as nutritious food.
The spouse-killing song of the same name probably harks back to some (real or imagined) withcraft implications of special foods ... but the psecifics are not important to the understanding or enjoyment of the song and its core trickery.
Regards,
Bob Bolton