Hullin 125: Do Bones Impart Impurity? Do Tents?

The marrow of a bone - in a sacrificial offering, that was then leftover - leads to impurity, as do the bones themselves. But that can depend on whether they are opened or closed. Also, touching impurity turns out to have the same status as one would have after carrying impurity. And raises the question of the "ohel," tent, for when impurity is transferred as a matter of being there, as per all of the different categories. Also, the "list' of the Mishnah plays out in the Gemara. Plus, defining the impurity of the tent ("ohel").