What happens to a buried body after years?
By 50 years in, your tissues will have liquefied and disappeared, leaving behind mummified skin and tendons. Eventually these too will disintegrate, and after 80 years in that coffin, your bones will crack as the soft collagen inside them deteriorates, leaving nothing but the brittle mineral frame behind.
However, on average, a body buried within a typical coffin usually starts to break down within a year, but takes up to a decade to fully decompose, leaving only the skeleton, Daniel Wescott (opens in new tab), director of the Forensic Anthropology Center at Texas State University, told Live Science.
As mentioned, even embalmed bodies are not spared from natural decomposition, which begins a few days to a week after embalming. For medical purposes and extenuating reasons, bodies can be kept for six months to two years. Bodies that are not embalmed, on the other hand, begin decomposing almost immediately.
It is a common practice to cover the legs as there is swelling in the feet and shoes don't fit. As part of funeral care, the body is dressed and preserved, with the prime focus on the face. Post embalming, bodies are often placed without shoes; hence covering the legs is the way to offer a dignified funeral.
(Note: If you're buried alive and breathing normally, you're likely to die from suffocation. A person can live on the air in a coffin for a little over five hours, tops. If you start hyperventilating, panicked that you've been buried alive, the oxygen will likely run out sooner.)
24-72 hours postmortem: internal organs begin to decompose due to cell death; the body begins to emit pungent odors; rigor mortis subsides. 3-5 days postmortem: as organs continue to decompose, bodily fluids leak from orifices; the skin turns a greenish color.
The difference is basically one of design. Coffins are tapered at the head and foot and are wide at the shoulders. Caskets are rectangular in shape and are usually constructed of better quality timbers and feature higher standards of workmanship.
What's really returned to you is the person's skeleton. Once you burn off all the water, soft tissue, organs, skin, hair, cremation container/casket, etc., what you're left with is bone. When complete, the bones are allowed to cool to a temperature that they can be handled and are placed into a processing machine.
Once a body is placed in a sealed casket, the gases from decomposing cannot escape anymore. As the pressure increases, the casket becomes like an overblown balloon. However, it's not going to explode like one. But it can spill out unpleasant fluids and gasses inside the casket.
Do they remove organs when you are embalmed? One of the most common questions people have about embalming is whether or not organs are removed. The answer is no; all of the organs remain in the body during the embalming process.
Can a person still be alive after being embalmed?
That said, it's possible for people to survive being injected with formaldehyde, Hoyte said. A person's survival would depend on the dose given, but because this situation is so rare, doctors don't really know what a fatal or non-fatal dose would be.
Putrefaction (4-10 days after death) – Autolysis occurs and gases (odor) and discoloration starts. Black putrefaction (10-20 days after death) – exposed skin turns black, bloating collapses and fluids are released from the body.

What Does This Mean for Our Future? Today, some cemeteries rent out plots, which allows people to lease a space for up to 100 years before the grave is allowed to be recycled and reused. Many countries around the world have resorted to this process as their available land begins to fill.
By ten-years, given enough moisture, the wet, low-oxygen environment sets off a chemical reaction that will turn the fat in the thighs and bottom to a soap-like substance called grave wax. However, in drier conditions, the body could also be mummified – that's mummification without wrappings, or chemicals.
Because, after 100 years, the last of your bones will have collapsed into dust. In fact, only the teeth will be left, given that they are the most durable part of your body.