Moss Stone looks like Cobblestone, but with moss growing on it. Like Cobblestone, on the upper left, there is an 'L' that points to the north and east. But unlike standard Cobblestone, Moss Stone cannot be smelted or crafted into anything. The only use is for construction - often used in combination with normal Cobblestone for decoration purposes, such as to make buildings look older or to make Nether portals more eerie. It is currently only found naturally as collections of 20-68 at a time in underground Dungeons.