Nick Upton / Flat periwinkle (Littorina obtusata / littoralis) yellow form crawling over rocks exposed at low tide, Cornwall, UK, March.

Nick Upton / Flat periwinkle (Littorina obtusata), yellow form crawling over Spiral wrack (Fucus spiralis). Treyarnon Bay, Cornwall England, UK. September.

Nick Upton / Flat periwinkle (Littorina obtusata), yellow form from Atlantic Ocean. Cornwall, England, UK. September.

Alex Hyde / Common Hermit Crab (Pagurus bernhardus) in Flat Periwincle shell (Littorina obtusata). Isle of Mull, Scotland, UK. June.

Sue Daly / Smooth periwinkles (Littorina obtusata) on kelp, Derrible Bay, Sark, British Channel Islands.

Alex Hyde / Common Hermit Crab (Pagurus bernhardus) in shell of Edible Periwinkle (Littorina littorea). This close up shows the compound eyes. Northumberland, UK. May.

Alex Hyde / Common Hermit Crab (Pagurus bernhardus) in shell of Edible Periwinkle (Littorina littorea). Photographed on a white background in mobile field studio. Northumberland, UK. May.

Alex Hyde / Common Hermit Crab (Pagurus bernhardus) in shell of Edible Periwinkle (Littorina littorea). Photographed on a white background in mobile field studio. Northumberland, UK. May.

MYN / Carsten Krieger / Flat Periwinkle (Littorina obstusata) from rock pool, County Clare, Republic of Ireland, August. Meetyourneighbours.net project

MYN / Carsten Krieger / Flat Periwinkle (Littorina obtusata) from tide pool, County Clare, Republic of Ireland, August. Meetyourneighbours.net project

MYN / Carsten Krieger / Flat Periwinkle (Littorna obtusata) on Bladderwrack (Fucus vesiculosus) from tide pool, County Clare, Republic of Ireland, December. Meetyourneighbours.net project

Nick Upton / European oyster drill / Sting winkle (Ocenebra erinacea) a pest of oyster beds, on rocks low on the shore alongside Acorn barnacles (Balanus perforatus) exposed at low tide, with seaweed, rock pools a...

Philippe Clement / Sting winkle / Oyster drill / Hedgehog Murex (Ocenebra erinacea) shells on beach, Brittany, France

Ernie Janes / Fisherman returning with bucket of Winkles and bicycle, Blakeney Harbour, Norfolk, UK, September

Philippe Clement / Sting winkle / Oyster drill / Hedgehog Murex (Ocenebra erinacea) shells, Brittany, France

Philippe Clement / Sting winkle / Oyster drill / Hedgehog Murex (Ocenebra erinacea) on beach, Brittany, France

Philippe Clement / Oyster drill / Sting winkle / Hedgehog murex (Ocenebra erinacea) shell, Mediterranean, France

Philippe Clement / Oyster drill / Sting winkle / Hedgehog Murex (Ocenebra erinacea) shell on beach, Mediterranean, France

Philippe Clement / Oyster drill / Sting winkle / Hedgehog Murex (Ocenebra erinacea) shell showing aperture, Mediterranean, France

Nick Upton / European oyster drill / Sting winkle (Ocenebra erinacea) a pest of oyster beds, on the move over rocks very low on the shore, near Falmouth, Cornwall, UK, August.

Nick Upton / European oyster drill / Sting winkle (Ocenebra erinacea) a pest of oyster beds, on the move over Coralweed (Corallina officinalis) in a low shore rockpool, near Falmouth, Cornwall, UK, August.

Sergio Hanquet / Blue starfish (Coscinasterias tenuispina) arms capturing Red-mouthed rock-shell (Stramonita haemastoma), Tenerife, Canary Islands, Atlantic Ocean.

Sergio Hanquet / Blue starfish (Coscinasterias tenuispina) arm capturing Red-mouthed rock-shell (Stramonita haemastoma), Tenerife, Canary Islands, Atlantic Ocean.

Mike Potts / Carrion crow (Corvus corone ) with Winkle (Littorina littorea) in beak, foraging on shore at low tide, Penrhyn Bay, Conwy, North Wales, UK. March.

Mike Potts / Carrion crow (Corvus corone ) in flight carrying Winkle (Littorina littorea) in beak, with wind farm in background, Penrhyn Bay, Conwy, North Wales, UK. January.

Mike Potts / Carrion crow (Corvus corone ) feeding on Winkles (Littorina littorea) at low tide amongst seaweed, Penrhyn Bay, Conwy, North Wales, UK. April.

Alex Mustard / Life in a rockpool, including acorn barnacles (unidentified), black-footed limpets (Patella depressa), common limpets (Patella vulgata) and common periwinkles (Littorina littorea). Falmouth, Cornwall,...

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.

Robert Thompson / Rough periwinkle (Littorina saxatilis) Killard Point, NNR Ballyhornan, County Down, Northern Ireland.

Robert Thompson / Rough periwinkle (Littorina saxatilis) Killard Point, NNR Ballyhornan, County Down, Northern Ireland.

Alex Hyde / Trails left on sand-covered rock from Edible periwinkle (Littorina littorea) grazing on algae. Cornwall, UK. May.

Nick Upton / Land winkle / Round-mouthed snail (Pomatias elegans), a land snail closely related to marine snails, positioned to show its tough operculum, on a chalk grassland slope, near Bradford on Avon, Wiltshir...

Nick Upton / Land winkle / Round-mouthed snail (Pomatias elegans), a land snail with an operculum, closely related to marine snails, emerging from its shell on a chalk grassland slope, near Bradford on Avon, Wilts...

Nick Upton / Land winkle / Round-mouthed snail (Pomatias elegans), a land snail with an operculum, closely related to marine snails, on the move on a chalk grassland slope, near Bradford on Avon, Wiltshire, UK, Ju...

Nick Upton / Land winkle / Round-mouthed snail (Pomatias elegans), a land snail with an operculum, closely related to marine snails, on the move on a chalk grassland slope, near Bradford on Avon, Wiltshire, UK, Ju...

Alex Mustard / Spiral wrack (Fucus spiralis) with fruiting bodies photographed in a rock pool, with common periwinkle (Littorina littorea). Looe, Cornwall, England, United Kingdom. English Channel, North East Atlant...

Alex Mustard / Aggregation of Common periwinkles (Littorina littorea) gather in a rock pool. Looe, Cornwall, England, United Kingdom. English Channel, North East Atlantic.

Nick Upton / Common / Edible periwinkle (Littorina littorea) crawling over a rockpool floor, The Gower Peninsula, UK, August.