Mycelium

Mycelium is a unique block in Minecraft, similar to grass blocks but found naturally only in mushroom fields biomes. The top of mycelium blocks has a particle effect that resembles tiny spores being released constantly. It can spread to nearby dirt blocks, similar to how grass does. Mycelium needs a light level of 9 or higher above it, while the dirt block needs a light level of 4 or higher for spreading to occur, and cannot be covered by any opaque or light-blocking block. If there is insufficient light or if it is blocked, mycelium will revert to dirt. When mycelium spreads to dirt blocks with plants, the plants will pop off. Using a tool with the Silk Touch enchantment to mine mycelium blocks will yield the mycelium block itself, otherwise it will drop dirt. Mycelium is also a good place for mushrooms to grow; they grow faster on mycelium than on other blocks and can remain even if the light level is usually too high. Mycelium can also be used to create dirt paths.