MYN / Jerry Monkman / Green sea urchin (Strongylocentrotus droebachiensiss) Rye, New Hampshire, USA, August. meetyourneighbours.net project

Jeff Rotman / Green sea urchins (Stronglyocentrotus droebachiensiss) scavenging and grazing, USA, North Atlantic Ocean.

Alex Hyde / Underside of Green Sea Urchin (Psammechinus miliaris) with mouth visible in centre. Isle of Mull, Scotland. June 2010.

Alex Hyde / Green Sea Urchin (Psammechinus miliaris) in a rockpool, Isle of Mull, Scotland. June 2010.

Alex Hyde / Green Sea Urchin (Psammechinus miliaris) Isle of Mull, Scotland. June 2010.

Robert Thompson / Green sea urchin {Psammechinus miliaris} County Down, Northern Ireland, UK, September

Robert Thompson / Green sea urchin {Psammechinus miliaris} Ballyhenry Point, Strangford Lough, County Down, Northern Ireland, UK, September

Robert Thompson / Green sea urchin {Psammechinus miliaris}

Wild Wonders of Europe / Banfi / Rock covered with Encrusting sponge (Spirastrella cunctatrix) and Sea urchin (Arbacia lixula) and Green ball (Codium bursa) Larvotto Marine Reserve, Monaco, Mediterranean Sea, July 2009

Philippe Clement / Green sea urchin (Psammechinus miliaris) shell on beach, Belgium

Philippe Clement / Green sea urchin (Psammechinus miliaris), Normandy, France

Philippe Clement / Green sea urchin (Psammechinus miliaris) on beach, Normandy, France