The rabbis’ task in their reconstruction of the biblical laws of corpse impurity is to determine at which point a dead body in its fragmented and ruined state is still a “corpse” that can convey impurity, and at which point it is so disintegrated and decomposed that it can only be seen as organic matter, incapable of conveying impurity any longer. This task is taken on by creating a graded scale of corpse purity, onto which corpse parts and fragments are mapped as having diff erent degrees of ability to convey impurity.

–Mira Balberg, Purity, Body, and Self in Early Rabbinic Literature, pp.99-100