Falling boulders are dangerous, since they kill everything on its way. You can shift single boulders and move them to where they are needed. Blocks Blocks are similar to boulders, but they are indestructible. And they can be stacked without rolling off. These walls can be destroyed by creating an explosion next to it.
Some walls look like brick walls, but grow if there is space.
Magic walls These walls, too, look like normal brick walls, but they can be used to convert boulders to diamonds. Drop a boulder on a magic wall. If there is an empty field below it, the boulder will fall through as a gem. Unfortunately this only works for a short time and only once. Diamonds falling through a magic wall are transformed to boulders.