A Grass Block is a basic block that was introduced very early in the game. It uses 3 textures: the first is a gray one for the top. This is known as Mycelium, the ground block that spawns in Mushroom biomes. Next is one borrowed from the Dirt block for the bottom, and last is an edited dirt texture with grass on the top edge on all of the sides. When covered by Snow, the side texture is white. On natural maps, Grass appears on the topmost blocks of Dirt with no fluids or opaque solid blocks above them.