Fungal mycelium growing in decaying wood. For much of their lives, fungi can be hidden from view, only revealing themselves when they produce fruiting bodies to release spores. Digging down into damp woodland leaf litter or gently peeling back the bark on section of decaying log will quickly reveal a mass of fine thread-like structures, the fungal mycelium. Constructed from thousands of tiny tubes known as hyphae, the mycelium enables the fungus to absorb nutrients from the environment. Mycelium is central to nutrient recycling and itself is vital food source for a huge number of invertebrates. Derbyshire, UK. August.