Shifting away from the animal sacrifices of Tractate Zevahim to grain-offerings and the particulars of offering from grain. The first key aspect of a grain-offering is removing a fistful of grain from it, and the parallel is drawn between the handling of it and that of the blood that was collected from animal sacrifice for the altar. Opening with a new mishnah, of course: If that fistful were taken, but not in the name of the offering being brought - the offering is still valid except for a sin-offering and a "minhah kenaot" - a "jealousy" offering that is brought by the Sotah woman. Also, the various kinds preparation of grain-offerings (all of which would be fit) - a flat griddle fried cake, a more spongy dough, etc. So if the kohen offered one in place of the other, with wrong intent, it's still clear what was done, and it leaves the grain-offering fit because it's identifiable. Note the difference between a grain-offering that is brought because the given offering is supposed to be from grain, as compared to when one is offered for the sake of an animal sacrifice, but when there was some reason that the animal wouldn't be brought.