[Regarding] a leaven container [that is] surrounded by a sealed cover and placed into an oven, [if] leaven and a sheretz are in it and the dividing wall is between them, the oven is tamei, but the leaven is tahor. And if there was an olive’s volume [piece] from a corpse, the oven and [everything in] the house are tamei, but the leaven is tahor. But if there is an opening of one tefach, everything is tamei.