Astudan

Excarnation, the removal of flesh by carrion birds, was a common form of funereal practice in the ancient world, and especially in the east. Bodies were placed on towers with high platforms and left for the birds and elements to consume, so that only the bones remained. These dakhma or 'towers of silence' were usually outside a settlement, as the bodies of the dead were considered unclean. Bones were eventually collected and placed in ossuaries, either within the tower or at a nearby shrine. In Zoroastrianism, where a body would contaminate the purity of earth and fire, its excarnated remains were placed inside a well-like structure known as an astudan; lime and rainwater were then used to disintegrate the bones. After being filtered through charcoal and sand, the water would be allowed to flow away.