Minecraft wiki entry for End_Rod, associated text: End rods are primarily used as light sources and decoration. They can be placed on any surface of any block, including other end rods. They do not break if their supporting block is broken. Gravity-affected blocks like sand or gravel do not break if they fall onto an end rod oriented vertically, but they do break on a rod oriented horizontally. End rods can be pushed and pulled by pistons, no matter the orientation.