Mycelium is often described as the "root structure" or the "vegetative state" of fungi. These terms come from plants, but fungi are an entirely separate kingdom of life, distinct from animals, plants, or bacteria. Mycelium resembles roots, with its intricate networks of thread-like branching cells called hyphae. However, mycelial networks are unique—extremely fine and strong, with high tensile strength and the ability to resist water, decay, and immense internal or external pressures. They come from nature and, under the right conditions, return to nature as nutrients. In other words, they are one of nature’s most astonishing supermaterials.