"Your belly button may be more than a mere catchment zone for human detritus."
https://www.sciencealert.com/the-smell-of-your-belly-button-may-carry-signs-of-parkinsons-and-cognitive-decline?utm_source=join1440&utm_medium=email&utm_placement=newsletter&user_id=66c4c92f5d78644b3ac5d5b4