Scytonema
Scytonema is a genus of photosynthetic cyanobacteria that contains over 100 species. It grows in filaments that form dark mats. Many species are aquatic and are either free-floating or grow attached to a submerged substrate, while others species grow on terrestrial rocks, wood, soil, or plants. Scytonema is a nitrogen fixer, and can provide fixed nitrogen to the leaves of plants on which it is growing. Some species of Scytonema form a symbiotic relationship with fungi to produce a lichen.
Scyptolins are a type of elastase inhibitors isolated from some species of Scytonema.
A study comparing red macroalgae to Scytonema species showed their potential for cosmetical use, both for their antioxidants properties and photoprotection capacities due to their compounds Mycosporine-like [amino acid|MAAs], and scytonemin. This study indicated that they could be used as photoprotectors absorbing both in the UV-B and UV-A.