Mishná sobre Oholot 11:11

If a rooster that swallowed a sheretz fell within the air-space of an oven, the oven remains clean; If the rooster died, the oven becomes unclean. If a sheretz was found in an oven, any bread in it contracts second degree impurity since the oven is of the first degree.

Hatat water that became invalid, it may not be mixed into the mud since it might become a snare for others. Rabbi Judah says: it becomes neutralized. A cow that drank of the hatat water, its flesh becomes unclean for twenty-four hours. Rabbi Judah says: it becomes neutralized in its bowels.

The following vessels protect their contents when they have a tightly fitting cover: those made of cattle dung, of stone, of clay, of earthenware, of sodium carbonate, of the bones of a fish or of its skin, or of the bones of any animal of the sea or of its skin, and wooden vessels that are always clean. They protect whether the covers close their mouths or their sides, whether they stand on their bottoms or lean on their sides. If they were turned over with their mouths downwards they afford protection to all that is beneath them to the nethermost deep. Rabbi Eliezer declares this unclean. These protect everything, except that an earthen vessel protects only foods, liquids and earthen vessels.