In this chapter, we learn that the undead are supposed to eat the things that keep them going, even when they are in their "turbid" state for a long time. This is why they call them "zombies" . After a month or so in this state, the undead's brain has completely rotted away, and they enter the "fresh" state, where they can eat whatever they want. They're supposed to be able to check their brain waves in the event that something happens, but they're not yet able to do so.