The ritual precinct of the towers of silence may only be entered by a special class of pallbearers. Once the bones have been bleached by the sun and wind, which can take as long as a year, they are collected in an ossuary pit at the center of the tower and/or are eventually washed out to sea. In Parsi Zoroastrian tradition (India), exposure of the dead is additionally considered to be an individual's final act of charity, in sustaining the birds.