Alex Mustard / Black-lined periwinkle (Littorina compressa) on a bed of gutweed (Ulva intestinalis). St Brides Haven, Pembrokeshire, Wales, United Kingdom. British Isles. Irish Sea.

Philippe Clement / Clump of Enteromorpha / Ulva species of the green algae Gutweed (Ulvaceae) growing on rock on the beach at low tide, Normandy, France. August 2020

Philippe Clement / Gutweed / Sea lettuce (Ulva intestinalis / Enteromorpha intestinalis) green alga washed on rocky beach, Normandy, France, June

Philippe Clement / Gutweed (Ulva intestinalis / Enteromorpha intestinalis), sea lettuce (Ulva lactuca) and spiral wrack / flat wrack (Fucus spiralis) washed on beach, Normandy, France, June