Phylum: Rhodophyta   Family: Corallinaceae

Lithothamnion glaciale Kjellman, 1883

Red Encrusting Alga

It's hard to believe that the pink coating on rocks between the middle and lower shore is calcareous algae. It has two forms; one is unattached, the other encrusting. Both produce nodules, branched in the unattached form

References: 
Fish & Fish (2011) - A Student's Guide to the Seashore;
Bunker, et al - Seaweeds of Britain and Ireland;
Hiscock (1986) - A Field Key to the British Red Seaweeds