Zero Kama play occult, ritualistic, tribal music on bizarre sounding instruments that the insert states: "…were exclusively made from human bones and skulls by the hand of Zero Kama." I don't know if that's true, but it's certainly possible. It's percussion-based with the occasional wind-style instrument (hollowed out femur?) to accompany and lift the repetition. You'll need an appreciation of tribal rhythms and the sound of rattling bones to even make it past the first track.