 "Niebla marinii" is distinguished by the thallus divided into linear-subterete or linear-prismatic branches from a common attachment base (or holdfast); the primary branches often tubular inflated near base with a glossy smooth cortex, dividing frequently into equal secondary branches above, the branches wide spreading, arcuate or horseshoe shaped, densely tangled together, terminally flexuous or whip-like; the whole thallus to 15 cm in diameter and 6 cm high.The species ("N. marinii") also recognized by containing salazinic acid, without triterpenes, but often with an unknown, possibly scabrosin derivative.Pycnidia are prominent at tips of branches and on the upper parts of branches.