Species:

Note: The species is common in the intertidal and shallow subtidal along the coast of Norway during spring. Thallus is normally up to 5 cm long. The blades are monostromatic (one cell layer), and irregularly torn. Each individual starts to grow as a closed monostromatic sac, which tears open. The blade-like thallus represents the gametophytic generation, while the single-celled sporophyte (Codiolum stage) is found in calcareous substrate, like shells.