The cover of a grave and its support convey tumah if touched and through ohel, but not if they are carried. R’ Eliezer says: They do convey tumah if they are carried. R’ Yehoshua says: If underneath them there is earth from the graves, they convey tu-mah when carried, and if not, they do not convey tumah when carried. What is a support? That upon which the cover [itself] rests. However, a sup- port for a support is tahor.

These items are tahor if they become diminished: an olive’s volume of a corpse; an olive’s volume of netzel; a ladleful of corpse powder; a quarter [-log] of blood; a bone the size of a barleycorn; and a limb, [that was severed] from a living person, whose bone is incomplete.