What is the ruling on finding a part of a deceased person after burial?

Primary text

If a part of the deceased is found after the burial, it must be washed (ghusl), the funeral prayer (Salat al-Janazah) must be performed over it, and it must be buried beside the original grave. Alternatively, the original grave may be uncovered to place the lost part therein. There is no necessity to unearth the entire deceased body for this purpose.