Reference for Tevul Yom 3:3
חוּט שֶׁל בֵּיצָה שֶׁקָּרַם עַל דְּפָנוֹת שֶׁל לְפָס, וְנָגַע בּוֹ טְבוּל יוֹם, מִן הַשָּׂפָה וְלִפְנִים, חִבּוּר. מִן הַשָּׂפָה וְלַחוּץ, אֵינוֹ חִבּוּר. רַבִּי יוֹסֵי אוֹמֵר, חוּט וְכָל שֶׁנִּקְלָף עִמּוֹ. וְכֵן בְּקִטְנִיּוֹת שֶׁקָּרְמוּ עַל שְׂפָתָהּ שֶׁל קְדֵרָה:
Regarding a streak of an egg that congealed on the sides of a pan [containing a <i>terumah</i> dish], and a <i> tevul yom</i> touched it, if [he touched it] from the rim inwards, it is considered connected [to the food in the pan, and renders it impure]; if [he touched] from the rim outwards, it is not considered connected. Rabbi Yose says: the streak and any part that is peeled away with it [are considered connected]. And similarly regarding legumes that congealed on the rim of a pot.