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.

[1] 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.

[2] 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 MAAs, and scytonemin (unique to Scytonema).