Coralina officinalis

Description:
Whitish-pink to lilac, calcified, articulated fronds, 60-70 (-120) mm high, axis cylindrical to compressed, repeatedly pinnate from and expanded discoid base, branchng often irregular. Growth form very variable, often stunted. In unfavourable habitats erect system vestigial, but extensive base may be present.

Habitat:
On rock, midtidal pools and drainage runnels, lower intertidal and shallow subtidal, widespread and abundant, especially on exposed coasts.

Similar species:
Haliptilon squamatum (Linnaeus) Johansen, L. Irvine et Webster, a species rarely found in lower-shore rock pools, has shield-shaped articulations but is difficult to distinguish from Corallina officinalis. Corallina elongata is smaller and more regularly branched.

(In: Seaweed Site - ©Michael D. Guiry - http://seaweed.ucg.ie/descriptions/Coroff.html)