Phylum: Rhodophyta   Family: Gracilariaceae

Gracilariopsis longissima (S.G. Gmelin) M. Steentoft, L.M. Irvine & W.F. Farnham, 1995

Long Wart Weed

Although a red alga, it is usually found dark brown or sometimes bleached to greenish. Can be up to a metre in length but more often less. An important species for the extraction of agar. Quite common

References: 
Dixon & Irvine (1997) - Seaweeds of the British Isles, Volume 1 Rhodophyta, Part 1 Introduction, Nemaliales, Gigartinales