It vanishes in summer. The forest floor holds no sign of it. Then autumn arrives. The beech trees drop their catkins, and within weeks, the Beech Disco appears. Small cups. Pale brown. No larger than a fingernail. They grow from the buried remains of last season's flowers. The cups are shallow, fleshy, attached by a short stem to the rotting catkin. At maturity, the inner surface becomes smooth and slightly darker. Spores eject upward. A puff of smoke if you tap the cup. By winter, the cups have collapsed. By spring, nothing remains. Habitat is restricted to forest floor litter directly beneath southern beech trees. Nothofagus fusca, Nothofagus menziesii, Nothofagus solandri. The fungus does not grow on wood. It does not grow on leaves. It grows exclusively on the reproductive debris of beech. Catkins. Seed husks. The woody cupules that once held the nuts. Without these specific substrates, the fungus cannot complete its life cycle. It waits in the soil as dormant sclerotia. Hard masses of mycelium that survive months or years. When beech flowers fall, the sclerotia germinate. The cups emerge. The timing is precise. Range across New Zealand corresponds exactly with southern beech distribution. North Island populations occur in Te Urewera, the central plateau near Tongariro, and the Tararua Ranges. South Island populations are widespread in Nelson, Marlborough Sounds, West Coast forests, Canterbury's high country, Otago, Fiordland, and Southland. Stewart Island hosts it where beech grows. The fungus does not occur in Northland, Auckland, Waikato, or any region without Nothofagus. Its range is the range of its host. Diet is saprotrophic. Ciboria amentacea decomposes the cellulose and lignin in beech catkins and cupules. It specialises. Other fungi can break down these tissues, but none match the speed of Beech Disco after a mast year. The decay takes weeks, not months. The catkins soften. They darken. They become part of the humus layer. The fungus leaves nothing recognisable behind. Only the empty cups remain briefly, then they too collapse. Threats are biological rather than landscape-wide. The removal of beech forest for pasture or plantation forestry eliminates the host tree and the substrate simultaneously. Introduced mammals also matter. Possums, rats, and deer all consume beech seed and flowers. When seed predation rates exceed 90 percent after mast events, few catkins reach the forest floor intact. The fungus cannot fruit without fallen reproductive material. Years of high predation effectively sterilise the habitat.