Moss Stone, also known as Mossy Cobblestone, was first introduced in the Survival Test and remains in all later versions of the game. It looks similar to Cobblestone, but with moss growing in its cracks. They primarily compose the floors of Dungeons as well as Jungle Temples.
Unlike standard cobblestone, moss stones cannot be smelted. They can, however, be crafted into a Mossy Cobblestone Wall. Their only use is in construction and they are often used in combination with normal cobblestone for decoration purposes, such as to make buildings look older or to make Nether Portals more eerie.