Ulva linza Linnaeus
Also known as Enteromorpha linza or Doubled Ribbon Weed.
Description: Thallus bright grass-green or light green, with an unbranched or sparingly branched ribbon-like, strongly compressed frond up to 30 cm long, generally with a frilled or scalloped margin; initially solid but becoming hollow below; frond tapering gradually to a solid stipe. Variable in form.
Habitat: Rock pools and growing on shells in damp depressions in the mid and lower intertidal, particularly in places affected by sand.
Distribution: Common through Britain and Ireland; North Atlantic and Mediterranean; seemingly widely distributed throughout the world but further study required.
Similar species: Ulva (Enteromorpha) compressa which is generally compressed, but hollow throughout and without scalloped edges.