Mossy Cobblestone

Moss Stone (previously known as Mossy Cobblestone) was first introduced in Survival Test and remains in all later versions of the game. It 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 to make buildings look old and ruined or to make nether portals more eerie. It is currently only found naturally as a collection of 30-64 at a time in underground Dungeons. However, in the upcoming 1.8 update, moss stone will be found in abandoned mine shafts and NPC Villages.

Moss Stone looks very similar to Netherrack in that both blocks are similarly textured, with Moss Stone being grey with green moss and Netherrack being bright-red with dark-red moss.



Future
Notch has stated that moss will grow on normal cobblestone in the future, and there is speculation that it will spread to other cobblestone blocks as well, making it similar to how Grass grows on Dirt, possibly in the dark instead of in the light. They also could be used on NPC Villages.

Trivia

 * In Beta 1.8 Moss Stone's texture was changed from this Moss Stone-Pre Beta 1.8.png to the current lighter version.