In Boxtrolls, are the boxes a natural part of troll society or is this a peculiar adaptation for this tribe?

In the movie, Boxtrolls, the trolls are apparently highly attached to their boxes, never seen without them, and reacting in horror when Eggs falls out of his.

I know this is partially based off of a book, ''Here Be Monsters!'', so it might be elaborated upon there. Are boxes a normal part of troll society? This particular group seems to be quite adapted to them. Or is it just this tribe?