Corpses sank in the Yangtze River. After the skin and flesh were eaten by fish, the bones sank to the bottom of the river.
Ordinary bones are fine. But bones sunk in "shady places" (backwater bays, ancient ferries, shipwrecks, water eyes) will be "lived in" by things in the water over time. Such bones are called bone guests.
When bone travelers come ashore, they will find living people to "borrow their lives" - first causing pain to a bone in a living person's body, and then "replacing" the living person's bones with their own bit by bit. The person who has been replaced becomes a new person, and the old person becomes a new person. This is called a substitute bone.
The technique handed down from the ancestors of the Chen family is to fish out the bones from the river before they come ashore and dispose of them by sealing the bones.
The bone collector does not pass on his surname, and he does not pass on his surname (that's the rule, but the story will break it).
