And they were amazed that the skin was still in tact - hanging loose around the dead man's skeleton.
Incredibly, dozens of tribal bamboo inkings done while the person was still alive show a black magic spell for nothing to ever penetrate the skin.
And excavators believe the Sanskrit writing and inkings of a tiger ensured the man's body stayed together and was prevented from rotting.
But in a cruel twist, it may have his strong skin that killed him as it was inpenetrable meaning he was unable to have an operation for fata appendicitis, according to rescue organisation Goopaitongdaeng Jeemokkho Goopainueng Soonpaed.
The Thai government organisation then shared the pictures online including one with the workers posing next to the body. .
A spokesman for the group said: ''The authority cleaned the cemetery with local people and volunteers and they found the skin of an old man who died of appendicitis. However, he couldn't have surgery because the skin was too hard to cut and he ended up dying in agonising pain from the illness.
"The skin has a lot of tattoos and it hasn't gone rotten. The spell to protect him and make him strong prevented the operation and then after he died stopped his skin from rotting."
Deeply superstitious Thais - the majority of whom believe in ghosts and reincarnation - were amazed when the images emerged.