Keilim9: 4
[ד] סְפוֹג שֶׁבָּלַע מַשְׁקִין טְמֵאִין וְנָגוּב מִבַּחוּץ, וְנָפַל לַאֲוִיר הַתַּנּוּר — טָמֵא, שֶׁסּוֹף מַשְׁקֶה לָצֵאת. וְכֵן חֲתִיכָה שֶׁל לֶפֶת וְשֶׁל גֶּמִי. רַבִּי שִׁמְעוֹן מְטַהֵר בִּשְׁנֵי אֵלּוּ.
[Regarding] a sponge that absorbed tamei beverages and was dry on the outside and it fell into the airspace of an oven, [the oven is] tamei, because the beverage will eventually emerge. And similarly a piece of turnip or of reed-grass. R’ Shimon rules tahor in these two [cases].