Mycelium is the surface block of the mushroom fields biome — one of the rarest naturally-spawning biomes in vanilla, generally found on isolated islands far from continental land. The texture is a dusty purple with tiny mushroom-spore particles drifting upward when the player stands nearby. The biome itself is uniquely peaceful: hostile mobs cannot spawn on this surface even at night, making mushroom islands the safest natural areas in the Overworld.

The block spreads to adjacent dirt blocks at random ticks under sufficient light, exactly like grass, allowing players to slowly transform a base into the mushroom aesthetic. Unlike grass, this surface allows mushroom growth at any light level — even in full sunlight — which is otherwise impossible. The biome is the only place where mooshrooms (cow variant with mushrooms growing on their backs) spawn, providing renewable mushroom-stew food. Mining without silk touch drops plain dirt; the visual variant requires the appropriate enchantment for capture.