The souls of people who die in resentment will always find ways to stay in this world. The flesh and blood of the body is the last connection between the souls in another world and this world. When even part of their body still exists, they can return to this world. Therefore, when the last trace of flesh and blood is burned out in the flames, and when the last piece of bone turns to ashes, the soul of the dead is closed to this world forever.
So... If there is such an organ... Its owner has died... It is now in your body...
You, be careful...