Just a note on the photo thE OP posted of possible "incorruption." The image of the Buddhist monk above is most likely Dashi-Dorzho Itigilov. As I looked at the photo, I presu,Ed the white powdery substance on his lower body was ice. It turns out it may have been salt - a preserving and mummifying agent that the body was packed in, according to investigative sources.
Anyway...there are many way that bodies are kept incorruption through natural mechanisms, such as the various "bog bodies" and, apparently - being pack in salt.
The following article talks about Dashi-Dorzho Itigilov, but also is fascinating because it speaks of a Japanese method of self mummification used by monks.
The steps involved in mummifying one’s own body were extremely rigorous and painful. For the first 1,000 days, the monks ceased all food except nuts, seeds, fruits and berries and they engaged in extensive physical activity to strip themselves of all body fat. For the next 1,000 days, their diet was restricted to bark and roots. Near the end of this period, they would drink poisonous tea made from the sap of the Urushi tree, which caused vomiting and a rapid loss of body fluids. It also acted as a preservative and killed off maggots and bacteria that would cause the body to decay after death.
In the final stage, after more than six years of torturous preparation, the monk would lock himself in a stone tomb barely larger than his body, where he would go into a state of meditation. He was seated in the lotus position, a position he would not move from until he died. A small air tube provided oxygen to the tomb. Each day, the monk rang a bell to let the outside world know he was still alive. When the bell stopped ringing, the tube was removed and the tomb sealed for the final thousand day period of the ritual