Monks who practiced sokushinbutsu sought transcendence through self-mummification. Their 3,000-day training process mandated a strict diet of foods such as nuts, berries, tree bark, and resin. Some monks also drank a sap that was traditionally used to make lacquer, and that may have helped to embalm the body from the inside out. Once the monk was ready, he would step into a small burial chamber that had an airway and a bell. He would ring the bell each day to let those on the outside know he was still alive. Once the bell stopped ringing, the airway was sealed.