Phylum: Rhodophyta   Family: Cystocloriaceae

Cystoclonium purpureum (Hudson) Batters, 1902

Purple Claw Weed

Very common bush alga, growing to 30-40 cm. Epilithic from the lower shore to subtidal

References: 
Bunker, Brodie, Maggs & Bunker (2017) - Seaweeds of Britain and Ireland;
Hiscock (1986) - A Field Key to the British Red Seaweeds