Codium fragile is a dark green alga, ranging from ten to 40 cm high and consists of repeatedly branching cylindrical segments about 0.5 to 1.0 cm in diameter, and the branches can be as thick as pencil. The segments look like dark green fingers. Its holdfast is a broad, sponge like cushion of tissue. The tips of segments are blunt and the surface is soft, so it is sometimes mistaken as a sponge. Its body consists of interwoven, filamentous cells with incomplete crosswalls forming the inner part of the branches.

Codium fragile is a green alga in the family Codiaceae in the Phylum Chlorophyta. The genus is Greek for kodion, meaning small sheepskin. Codium fragile appears as a fuzzy patch of repeatedly branching tubular fingers. These formations hang down from rocks during low tide, which serve as the inspiration for a few of its common names. The color of Codium fragile ranges from medium green to dark green to blackish green. The entire thallus is velvety and spongy in texture, relatively soft, and is sometimes tomentose with profuse hairs. The erect, dichotomously branched fronds, or fingers, are up to 1 centimeter wide, and can extend to lengths of over 30 centimeters. The branches of Codium fragile are round in cross section but may be flattened beneath dichotomies of branches. The fronds usually arise from a spongy disc-shaped holdfast, which resembles a small, broad cushion. A pungent odor is often associated with this species, which is less common for seaweeds.

Codium fragile is typically a species of the outer coast, found in both exposed and protected rocky shores on bedrock or boulders. It commonly inhabits the middle and lower intertidal zones of semi-exposed coasts and can be found less commonly in the subtidal on high energy beaches. Codium fragile also occupies large tide pools on rocky shores that are permanently filled with water.

Codium fragile is a siphonous alga, meaning that the entire organism is formed of interwoven and confluent filaments that lack crosswalls and that are in fact a single multinucleate cell (a "coenocyte"). This seaweed has no asexual (sporophyte) stage, and male and female gametes are produced on separate plants. Subspecies of Codium fragile are only distinguishable microscopically. Codium fragile is sometimes confused with Codium tomentosum, another commercial seaweed.

Link for Seaweeds Industry Association

Direct use as food - food, consumed whole; Contains: glucose; iron; mannans; mannose; polysaccharides; xylose

Other uses: Codium fragile is used for skin care and anti-aging products. Codium fragile is reported to be a regenerating and anti-free radical ingredient, and have rebalancing and energizing properties. Its wealth of macro-elements gives it a remineralizing property. One seller claims that Codium fragile is the ideal ingredient to boost tired and mature skin. Codium fragile is also used as food in eastern Asia.

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Common names used in trade, often for edible algae: dichotomous sponge tang; shui-sung {China}

In Inglish: Green sea fingers, dead man's fingers, felty fingers, green fleece, Oyster thief, dichotomous sponge tang.

Other names: algue chou-fleur, algue feutrée, algue feutre, codio fragil, codium orvet, dead man's fingers, felty fingers, felt-alga, Felt-Alge, Felt alge, felty fingers, forked felt alga, fragile codium, gaffelgrenet plysalge, green fleece, green sea fingers, green sponge, grüne Gabelalge, oyster thief, pollpryd, sea staghorn, shui-sung, sponge seaweed, spongeweed uk, Sputnik weed, vertakt viltwier, viltwier.

Basionym: Acanthocodium fragile Suringar

Type locality: Japan (Suringar 1867: 258). Type: L 910, 187...1712 (Womersley 1984: 238)