A fairy ring is a naturally occurring ring or arc of mushrooms, they can be so small that you would hardly notice them, or they can grow up to 600 m in diameter! They are mainly found in forested areas, but there are plenty that appear on grasslands.
Fairy ring formation begins with the fungus being spread by airborne spores that originate from the toadstool’s sporocarpus.
Most people associate fairy rings with the circle of mushrooms seen above ground, but there is far more to them than that, most of the organism is below ground, and it is the underlying mycelium that can cause the grass to wither and die through lack of nutrients.
The mycelium consists of a mass of branching, thread-like hyphae, which the fungus absorbs nutrients through, by secreting enzymes to break down the food source and then absorbs the broken down polymers.