Phylum: Rhodophyta   Family: Gracilariaceae

Gigartina pistillata (S.G. Gmelin) Stackhouse, 1809

Pestle Weed

Rare this far north with most records currently in the south-west. Very similar to Polyides rotunda but the flattened fonds separate it

References: 
Dixon & Irvine (1997) - Seaweeds of the British Isles, Volume 1 Rhodophyta, Part 1 Introduction, Nemaliales, Gigartinales;
Bunker, Brodie, Maggs & Bunker (2017) - Seaweeds of Britain and Ireland