Robert Thompson / Knotted wrack {Ascophyllum nodosum var mackii} and sea lettuce {Ulva sp} exposed at low tide, Ballyhenry Point, Strangford Lough, County Down, Northern Ireland, UK, August

Robert Thompson / Knotted wrack {Ascophyllum nodosum var mackii} exposed at low tide, Ballyhenry Point, Strangford Lough, County Down, Northern Ireland, UK, August

Robert Thompson / Knotted wrack {Ascophyllum nodosum} and Sea lettuce {Ulva intestinalis} exposed at low tide, Ballyhenry Point, Strangford Lough, County Down, Northern Ireland, UK, August

Niall Benvie / Dogwhelk {Nucella lapillus} egg cases amongst knotted wrack on strand line, Scottish Loch, UK

Ingo Arndt / Knotted Wrack (Ascophyllum nodosum) an edible seaweed sixteen centimeters, Helgoland, Germany

Ross Hoddinott / Knotted wrack seaweed {Ascophyllum nodosum} England

Ross Hoddinott / Knotted wrack seaweed {Ascophyllum nodosum} Cornwall, UK

Duncan Mcewan / Floating Knotted wrack {Ascophyllum nodosum}, Scotland

Niall Benvie / Knotted wrack seaweed, Loch Carron, Scotland

Niall Benvie / Knotted Wrack seaweed (Ascophyllum nodosum) Scotland

Niall Benvie / Knotted wrack seaweed (Ascophyllum nodosum) Scotland.

Nick Upton / Epiphytic red alga (Polysiphonia lanosa) growing in tufts on Knotted wrack (Ascophyllum nodosum) on a rocky shore, Wembury, Devon, UK, August.