1) THE TASTE ABSORBED IN THE BONES OF THE KORBAN PESACH
QUESTION: The Gemara discusses "Shimush Nosar," and whether it is considered significant or not. "Shimush Nosar" refers to an object that serves Nosar, such as a bone that preserves the marrow of Nosar inside it. If "Shimush Nosar" is significant, then the bone is Tamei like Nosar itself.
The Gemara suggests that according to the opinion that "Shimush Nosar" is not significant, the leftover bones of the Korban Pesach may be thrown away and do not need to be burned.
However, even if the fact that the bones "served" Nosar does not make them Nosar themselves, there is another reason to require that the bones be burned. The bones presumably absorbed the taste of the marrow, as well as the flesh, during the roasting, and that taste becomes Nosar and should require the bones to be burned.
ANSWER: One possible answer is that although the Torah prohibits eating Nosar that was absorbed, perhaps it does not require that Nosar that has become absorbed in another object be burned.
However, the RAN at the end of Avodah Zarah (DH Lo Asrah Torah) writes that the Torah requires Shetifah and Merikah (purging and rinsing in water) of a metal utensil, and the breaking of an earthenware utensil, that has absorbed the taste of Kodshim in order to destroy the Kodshim they have absorbed, which became Nosar. The Ran clearly implies that the absorbed taste of Nosar has the status of Nosar and must be burned. Since the utensils cannot be burned, the Torah provides a different procedure for destroying the taste of Nosar. (See also Insights to Zevachim 95:2.) Why, according to the Ran, is there no requirement to burn the bones of the Korban Pesach that have absorbed Nosar?
The MORDECHAI (Pesachim #1182) answers that bone does not absorb. He cites the Gemara here as proof that utensils made out of bone do not require Hag'alah for use on Pesach, because bone does not absorb. (The Mordechai, however, does mention other sources that seem to indicate that bone does absorb, but he does not reconcile those sources with the Gemara here.) (I. Segal)
2) ONE WHO FINDS BONES OF KODSHIM
QUESTION: Rav Mari bar Avuha says that bones which serve Nosar must be burned like the Nosar itself (see previous Insight). The Gemara questions this from a Beraisa which states, "All bones of Kodshim are not required to be burned" -- rather, as Rashi explains, the marrow of Nosar inside of them is removed and burned, and the bones may be discarded -- "except for the bones of the Korban Pesach," which must be burned because they may not be broken to remove the marrow. The Gemara proves from here that bones which serve Nosar are not like Nosar and do not need to be burned, because if they were like Nosar, then the bones of all other types of Kodshim should also be required to be burned.
Rav Nachman and Rav Zevid offer answers to defend Rav Mari bar Avuha's opinion that bones which serve Nosar are like the Nosar itself. It is evident from Rav Zevid's answer that he argues with Rav Nachman and maintains that when a person finds piles of Pesach bones from which the marrow has been removed, he does not need to burn them. Even though items which served Nosar are normally forbidden, and these Pesach bones might have served Nosar (the marrow that was inside of them), these bones do not have to be burned because we assume that the marrow was removed before it became Nosar, as Rashi (DH Atzmos) explains.
The MAHARSHA questions this assertion. How could the marrow have been removed before it became Nosar? Before it became Nosar, it was still edible, and the prohibition against breaking a bone of the Korban Pesach ("Sheviras Etzem") was in effect! Only after it becomes Nosar may one break the bone to remove the marrow (83a, according to Rebbi Shimon). Why, then, does Rav Zevid maintain that we assume that someone transgressed and broke the bones when he was not allowed to, before the marrow became Nosar, and thus the bones do not need to be burned? We should assume instead that the person did not transgress the prohibition of Sheviras Etzem and the bones were broken only after the marrow became Nosar (and thus the bones should be burned).
(a) The MAHARSHA answers that Rav Zevid follows the opinion of Rebbi Yakov, who maintains that even after the marrow becomes Nosar, the prohibition of Sheviras Etzem remains in effect. Therefore, whether one broke the bones before the marrow became Nosar or after it became Nosar, he transgressed the prohibition. In a case of a doubt we assume that the bones were broken (and the marrow removed) before the marrow became Nosar, and thus the bones do not need to be burned.
(b) This does not seem to be the approach of RASHI. Rashi explains that Rav Zevid argues with Rav Nachman, who says that we assume that the marrow was removed after the marrow became Nosar, and therefore the bones must be burned. If Rav Zevid merely follows the opinion of Rebbi Yakov, then he does not argue with Rav Nachman. Rav Nachman requires the bones to be burned only because he rules like Rebbi Shimon, who says that one is permitted to break the bones of the Korban Pesach after the marrow has become Nosar (and thus we assume that someone broke the bones when he was permitted to do so). Rav Zevid, however, rules like Rebbi Yakov, who says that the prohibition of Sheviras Etzem always applies.
Rashi apparently understands that Rav Zevid also follows the opinion of Rebbi Shimon and maintains that one is permitted to break the bones after the marrow has become Nosar. According to Rav Zevid, even though it is likely that the bones were broken after the marrow became Nosar (when one was permitted to break them), we still assume that they were broken before the marrow became Nosar (and the prohibition was transgressed) in order not to prohibit the bones as Nosar ("Shimush Nosar"). Since that possibility exists, and since the obligation to burn bones that served Nosar is not severe, we may assume that they were broken even unlawfully (when Sheviras Etzem was prohibited) and did not serve Nosar.