An Egregoria is the house of an egregore; which is just like a full cafeteria when it takes on a life of its own; except that the egregore is ideally a symbiotic entity if it both nourishes and is replenished by the group.
 When trolls do it
An egregore of trolls is an egregius, its egregoria is called a trollsnest. Their actual eating, lunching, bite you on the leg, etc., is referred to as a trollgnaw: Crocker's Rules apply to all who remain, not only those who accepted them in advance.
The distinction is useful to permit those who are not trolls to leave when an egregoria becomes a trollsnest or an egregore becomes an egregius or they get too bit on the leg.