Podzol

Podzol is a block that was added in Update 0.9.0. It is like Dirt except grass cannot grow on it. As of 0.9.1, Mossy cobblestone can be found on top of Podzol. Podzol can only be found in Mega Spruce Taiga biomes. Similar to Mycelium, mushrooms can grow on Podzol in any light level. Unlike Mycelium, Podzol doesn't spread to other dirt blocks.