Phylum: Rhodophyta   Family: Rhodomelaceae

Vertebrata lanosa (Linnaeus) T.A. Christensen, 1967

Wrack Siphon Weed

Can be found on several species of wrack but most common on Ascophyllum nodosum. A dioecious species with the separate branches looking quite different. Mostly within the mid to lower tidal range

References: 
Maggs & Hommersand (1993) - Seaweeds of the British Isles, Volume 1 Rhodophyta, Part 3A Ceramiales