Minecraft wiki entry for Honey_Block, associated text: When a honey block is moved by a piston, it attempts to move all adjacent blocks in the same direction. A honey block can move any block a sticky piston can pull, except for glazed terracotta and slime blocks. The blocks that are moved may, in turn, push other blocks, as if they were being pushed by a piston. For example, a honey block sitting on the ground attempts to move the ground block underneath itself, which pushes additional ground blocks in the direction of motion.