Volcanic rock is heated until red-hot and is placed in the center of an igloo-type construction, where the group reunites. After the initial ceremony, the conch shell is sounded, signaling the beginning of the temazcal bath. The group gets comfortable inside the temazcal and the stones are called for. The door is closed, sealing off all light and sealing in the heat. Herbs are thrown on the stones to create a curative vapor, heating the temazcal to even higher temperatures. The body may reach a temperature of 104°F ó 40° C during the temazcal.