השרץ

A sheretz

that was found

below the floor of a tanur,

[the tanur is] tahor,

as I can say

it fell [there] while alive

and [only] now is dead.

A needle or a ring (that were tamei)

that were found below the floor of a tanur

[the tanur is] tahor,

as I can say

it was there

from before the tanur had not yet come there;

if they are found in the dirt of a fire (i.e. they were found lying on top of ashes)

it is tamei

as there is nothing with which to explain them (there is no reasonable explanation for how they could have gotten there without passing through the airspace of the tanur).

פרק ט משנה ד

A sponge

that soaked up tamei beverages

and dried on its outside

and fell into the airspace of a tanur,

[the tanur] is tamei,

as the beverage would ultimately come out.

And similarly,

a piece of a turnip

and of a reed (these items were often used to soak up liquids, and if after having soaked up a tamei liquid they fell into a tanur, the tanur would be tamei);

Rabbi Shimon rules these two to be tahor.