Chulin 9:5-6

Chulin 9:5

If a person touches a bone containing marrow from a corpse or from consecrated animals, he is rendered ritually unclean; this is true regardless of whether the bone is plugged (rendering the marrow inaccessible) or pierced (so that the marrow can be extracted). If a person touches a bone containing marrow from a neveila or a sheretz (creeping creature), he remains clean if the bone is plugged but if it’s pierced even the smallest amount, it conveys ritual impurity through contact. We know that this also applies to carrying because Leviticus 11:39-40 says, “one who touches…one who carries.” Whatever applies to contact also applies to carrying and whatever doesn’t apply to contact doesn’t apply to carrying.

Chulin 9:6

The egg of a creeping creature in which an embryo has formed is ritually clean; if it is pierced – no matter how little – it is ritually unclean. If a person touches the flesh of a mouse that is partially made of flesh and partially made of earth, he is rendered ritually impure but if he touches the part that is made of earth, he remains ritually clean. Rabbi Yehuda says that one who touches the earth facing the flesh is also rendered ritually unclean. [This appears to refer to the ancient belief that mice spontaneously generated from the mud. Given the belief in such a creature, it’s hardly surprising that the Sages would report on what halachos would apply to it.]