Appearance
Thallus dark green (sometimes bluish), stiff, entwined, to 200 mm in length, composed of profusely, irregularly branched filaments apparent to the unaided eye. Attached by a rhizoidal holdfast. Persists throughout the year.Habitat
Grows on rock and in pools from mid-tide downwards, often growing under Fucus vesiculosus or Ascophyllum nodosumReferences:
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https://www.seaweed.ie/descriptions/Cladophora_rupestris.php