Rainbow Bricks are blocks obtained by killing Rainbow Slimes. Rainbow bricks shift quickly between multiple colors but do not produce light for the surrounding area. They can change the color of flowing water as it flows through blocks that have been shaped with a hammer. An illusion can be created by staring at a box of these bricks, they will seem to warp as they shift colors.
When the rainbow bricks are selected in the hotbar, taking any item out of its slot will make it rapidly shift color like the rainbow bricks.