As far as I know, there are two categories of bricks as of now; zone bricks (zone bricks, the coffin and to some extent certain terrain bricks and stuff), and regular bricks.
They can overlap eachother, however, you cannot place a coffin in a zone, and you cannot place a brick in a brick.
This is very convoluted and troublesome. if we could somehow get rid of these "categories" of bricks and just have stuff go in other stuff and not forget around so much, then that would be very nice!