Walking through a native forest on a pitch-black night can reveal a hidden wonder: the eerie, soft green light emanating from decaying wood. The glowing fungus, specifically the honey mushroom known scientifically as Armillaria novae-zelandiae, is one of the few species in New Zealand capable of true bioluminescence. Often referred to by enthusiasts as "foxfire", this phenomenon occurs within the mycelium of the fungus as it colonises dead wood. The light is produced by a chemical reaction involving a luciferin compound and an enzyme, luciferase, which oxidises to emit a steady, cold, blue-green glow. While the mushrooms themselves can sometimes display this light, it is most frequently observed in the fungal threads that lace through rotting logs and stumps, painting the forest floor with a faint, ghostly illumination that is truly captivating to witness. Beyond its magical appearance, this fungus plays a vital ecological role as a saprotroph. It is an aggressive decomposer, breaking down the complex structural components of wood, such as cellulose and lignin, in dead or dying trees. By recycling these nutrients back into the soil, it clears space and creates fertile ground for new growth, effectively acting as an essential engine of forest rejuvenation. The mycelium forms long, shoestring-like strands called rhizomorphs that can extend for significant distances through the soil and wood, allowing the fungus to spread efficiently from one resource to the next. When conditions are sufficiently moist, the fungus produces clusters of tawny-yellow mushrooms, often around the base of trees or on fallen timber, marking the reproductive phase of its lifecycle. For naturalists and photographers, witnessing this bioluminescent display is a rare and rewarding experience, requiring patience and dark-adapted eyes. It is important to remember that these fungi are sensitive to environmental disturbances. Because they rely on a steady supply of dead wood and stable microclimates, protecting fallen timber in our native forests is crucial for maintaining these living light shows. Visitors are encouraged to explore forest tracks at night with caution and respect for the delicate habitat. While this species is widespread, observing it requires minimal interference, as the delicate bioluminescence can be easily disrupted by artificial light or mechanical damage. Documenting these sightings on digital platforms aids researchers in understanding the distribution and ecological importance of bioluminescent species within New Zealand ecosystems, ensuring that this natural lantern continues to brighten our quietest forest corners for generations to come.