משנה על כלים 17:17

The following [objects serve to] reduce [the area of a square] handbreadth:[A portion] of less than an olive-size of flesh [of a corpse] reduces [the opening for uncleanness that is] caused by a quarter of a kav of bones [from a corpse]; [A portion] of less than a barley-corn size of bone reduces [the opening for uncleanness that is] caused by an olive-sized portion of flesh; Less than an olive-sized portion of a corpse, Less than an olive-sized portion of carrion, Less than a lentil-sized portion of sheretz; Less than an egg-sized portion of food; Produce growing next to the window, A cobweb having substance; The carcass of a clean bird that he did not intend to eat, And the carcass of an unclean bird that had been intended [for food] that had not been rendered susceptible [to uncleanness], or which had been rendered susceptible [to uncleanness] but had not been intended [for food].