Biotechnology startups across the United Kingdom are advancing a new class of sustainable materials: mycelium-based leather alternatives grown from fungal root networks instead of animal hides. Rather than raising livestock for years, these materials are cultivated in controlled environments where mycelium forms dense, sheet-like structures that can be harvested in just a few weeks. Mycelium—the underground root-like structure of fungi—naturally binds into strong, fibrous networks. By guiding it