Spider silk is a protein fiber spun by spiders. Spiders use their silk to make webs or other structures, which function as nets to catch other animals, or as nests or cocoons for protection for their offspring. Spider silk is as strong as many industrial fibers. There is commercial interest in duplicating spider silk artificially, since spiders use renewable materials as input and operate at room temperature, low pressures and using water as a solvent. However, it has been difficult to find a commercially viable process to mass produce spider silk.