קדירה

A pot

that was place inside a tanur,

if there is a sheretz in the tanur

the pot is tahor,

as earthenware utensils cannot impart tumah to utensils;

if there was sufficient liquid in it [the pot] to moisten,

it [the lquid] becomes tamei

and imparts tumah [to the pot].

Thus this [the pot] says:

"That which made you tamei did not make me tamei,

and you made me tamei."

פרק ח משנה ה

תרנגול

A chicken

that swallowed a sheretz

and fell into the airspace of a tanur,

the tanur is tahor;

and if it [the chicken] died (before it digested the sheretz) it [the tanur] is tamei.

A sheretz that is found in a tanur,

the bread inside of it is a sheni (a secondary source of tumah),

as the [airspace of the] tanur is a beginning (i.e. a progenitor of tumah)