Stereum hirsutum, commonly known as the Hairy Curtain Crust, is a wood-decay fungus found on decaying hardwoods, especially Oak and Beech. It forms thin, bracket-like fruiting bodies that are tightly attached to logs and fallen branches, appearing as wavy, semi-circular layers. The upper surface is velvety or hairy, often with concentric colour zones of orange, yellow, and brown, while the underside is yellow-brown, smooth and lacks pores or gills. It is a saprobic species, meaning it decomposes dead organic material, contributing to nutrient recycling in forest ecosystems. The fruiting bodies are tough and leathery, typically growing in dense, overlapping clusters. S. hirsutum is widely distributed in temperate regions across the globe and is often found year-round on fallen logs, stumps, or dead branches. It is sometimes mistaken for other crust fungi, but its hairy upper surface and distinct colouring help with identification. While not known for medicinal properties like some other fungi, S. hirsutum plays an important ecological role in breaking down lignin and cellulose, facilitating forest floor turnover.