TT #153 · Parshas Shemini · Aliyah 6 · Passuk 24
Chabad.org — Vayikra Chapter 11 with Rashi
English: And the following shall make you impure—whoever touches their carcass shall be impure until evening.
Chullin 126b.
E-Daf.com — Chullin 126b (Tsurras Hadaf)
כָּל הַנּוֹגֵעַ בְּנִבְלָתָם. תָּנוּ רַבָּנַן, בְּנִבְלָתָם וְלֹא בְּקוֹלִית סְתוּמָה, יָכוֹל אֲפִלּוּ נִקְּבָה, תַּלְמוּד לוֹמַר הַנּוֹגֵעַ יִטְמָא, אֶת שֶׁאֶפְשָׁר לִגַּע טָמֵא וְאֶת שֶׁאִי אֶפְשָׁר לִגַּע טָהוֹר.
Textual precision — The wording limits impurity to contact with a carcass in a condition that can actually be touched.
A closed hollow bone does not convey the stated impurity because the inner material cannot be touched; a perforated bone can.