A bezoar stone
the large stone mounted in silver and hung on an elaborate woven silver strap, circa 1680.
Bezoar stones are found in the intestines of animals. They are formed by indigestible materials being surrounded by layers of calcium and magnesium phosphate, which stomach contractions squeeze into a rounded shape.
The name bezoar is derived from the Persian word pa(d)zhar meaning ‘antidote against poison’. According to legend, bezoar stones gave protection against plagues and deflected evil spirits.