Andrew Parkinson / Dunlin (Calidris alpina) adult trying to pull a worm out of the wet sand, September, Shetland Islands, UK, September.

Pascal Kobeh / Bobbit worm (Eunice aphroditois) in sand on sea floor, at night. Flores Sea, Indonesia.

Pascal Kobeh / Henshaw's snake eel (Brachysomophis henshawi) burried in the sand, Sulu sea, Philippines

Pascal Kobeh / Henshaw's snake eel (Brachysomophis henshawi) buried in the sand, Sulu sea, Philippines

Pascal Kobeh / Black finned snake eel (Ophichthus melanochir) buried in the sand, Sulu Sea, Philippines

Nick Upton / Honeycomb worm (Sabellaria alveolata) reef. Clustered tubes built of sand grains attached to rocks, exposed at low tide. Duckpool Beach, Cornwall, Devon, UK. September 2018.

David Fleetham / Freckled snake eel (Callechelys lutea) head poking out of sand with rest of body buried. Hawaii.

Tony Wu / Snake eel (Ophisurus macrorhynchos) waiting to ambush prey, head poking out of sand. Sue, Wakayama Prefecture, Kansai, Honshu, Japan. February.

Konrad Wothe / Lugworm / Sandworm (Arenicola marina) holes and casts on mudflats, on the coast of the North Sea, Germany, June.

Franco Banfi / Crocodile snake eel (Brachysomophis crocodilinus) hiding in sand, Pura Vida House Reef, Dumaguete, East Negros Island, Central Visayas, Philippines, Pacific Ocean.

Luis Quinta / Mint-sauce worms (Symsagittifera roscoffensis / Convoluta roscoffensis) sunbathing on sand at low tide to allow the symbiotic algae to photosynthesise. Costa de Caparica beach, Portugal. April 2017.

Luis Quinta / Patterns made in sand by Mint-sauce worms (Symsagittifera roscoffensis / Convoluta roscoffensis) sunbathing at low tide to allow the symbiotic algae to photosynthesise with bivalve shell . Costa de Ca...

Luis Quinta / Patterns made in sand by Mint-sauce worms (Symsagittifera roscoffensis / Convoluta roscoffensis) sunbathing at low tide to allow the symbiotic algae to photosynthesise. Costa de Caparica beach, Portug...

Luis Quinta / Patterns made in sand by Mint-sauce worms (Symsagittifera roscoffensis / Convoluta roscoffensis) sunbathing at low tide to allow the symbiotic algae to photosynthesise. Costa de Caparica beach, Port...

Luis Quinta / Mint-sauce worms (Symsagittifera roscoffensis / Convoluta roscoffensis) sunbathing on sand at low tide to allow the symbiotic algae to photosynthesise. Costa de Caparica beach, Portugal. April 2017.

Alex Mustard / Bobbit worm (Eunice sp.) emerges from its hole in black sand at night to feed. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Filter feeding appendages of a Yellow california horseshoe worm (Phoronopsis californica) extending from the sand. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Georgette Douwma / Napoleon snake eel (Ophichthus bonaparte) swimming over sand. Lembeh Strait, North Sulawesi, Indonesia.

Pascal Kobeh / Bonapart's / Napoleon snake eel (Ophichthus bonaparti) head sticking out of sand, Sulu Sea, Philippines

Gerrit Vyn / Greater sand plover (Charadrius leschenaultii) in winter plumage with worm prey. Rakhine State, Myanmar. January.

Alex Mustard / Marbled snake eel (Callechelys marmoratus) thrusts its head out of sand, stiring up the sediment. Nuweiba, Sinai, Egypt. Gulf of Aqaba, Red Sea.

Adrian Davies / Lugworm (Arenicola marina) casts on a beach, Shetland Islands, Scotland, UK, November.

Adrian Davies / Lugworm (Arenicola marina) casts on a beach, Shetland Islands, Scotland, UK, November.

Solvin Zankl / Lugworm (Arenicola marina) cast on beach, on beach of Wadden sea, Heligoland, Germany, June.

Alex Hyde / Lugworm (Arenicola maritima) feeding depression on sandy shore at low tide, Colwyn Bay, Wales, UK. May.

Alex Hyde / Sand Mason Worms (Lanice conchilega) tube in sand on beach, Colwyn Bay, Wales, UK. May.

Alex Hyde / Sand Mason Worms (Lanice conchilega) tube in sand on beach, Colwyn Bay, Wales, UK. May.

Alex Hyde / Ice Cream Cone Worm (Pectinaria koreni) sand casings, Colwyn Bay, Wales, UK. May.

Alex Hyde / Lugworm (Arenicola maritima) cast and feeding depression on sandy shore at low tide, Colwyn Bay, Wales, UK. May.

Alex Hyde / Sand Mason Worms (Lanice conchilega) tube in sand on beach, Colwyn Bay, Wales, UK. May.

Alex Hyde / Sand Mason Worm (Lanice conchilega) tube in sand on beach, Colwyn Bay, Wales, UK. May.

Jiri Slama / Semipalmated Plover (Charadrius semipalmatus) pulling a worm out of the sand, Florida

Nick Upton / Close up view of Sand mason worm (Lanice conchilega) fringed tube reinforced with sand and shell fragments exposed on a low spring tide on a sandy shore at Rhossili, The Gower peninsula, UK, July.

Nick Upton / Close up view of Sand mason worm (Lanice conchilega) fringed tube reinforced with sand and shell fragments exposed on a low spring tide on a sandy shore at Rhossili, The Gower peninsula, UK, July.

Nick Upton / Sand mason worm (Lanice conchilega) tube reinforced with sand and shell fragments exposed on a low spring tide on Rhossili beach with the sea and Worm's head in the background, The Gower peninsula, UK...

Nick Upton / Sand mason worm (Lanice conchilega) fringed tube reinforced with sand and shell fragments exposed on a low spring tide on a sandy shore at Rhossili, The Gower peninsula, UK, July.

Nick Upton / Wide angle view of Sand mason worm (Lanice conchilega) tubes reinforced with sand and shell fragments exposed on a low spring tide on a sandy shore, with the sea in the background, Rhossili, The Gower...

Nick Upton / Sand mason worm (Lanice conchilega) tubes reinforced with sand and shell fragments exposed on a low spring tide on a sandy shore, with the sea in the background, Rhossili, The Gower peninsula, UK, Jul...

Nick Upton / Sand mason worm (Lanice conchilega) tube reinforced with sand and shell fragments exposed on a low spring tide on Rhossili beach with the sea and Worm's head in the background, The Gower peninsula, UK...

Nick Upton / Sand mason worm (Lanice conchilega) fringed tube reinforced with sand and shell fragments exposed on a low spring tide on a sandy shore at Rhossili, The Gower peninsula, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide with the sea in the background, St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide, alongside Saw wrack (Fucus serratus) St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide, alongside Saw wrack (Fucus serratus) St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide, St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide, St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide with the barnacle encrusted boulders and the sea in the background, St.Be...

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide with the sea in the background, St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide, St.Bees, Cumbria, UK, July.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide with the sea in the background, St.Bees, Cumbria, UK, July.

Ernie Janes / Sand mason worm (Lanice conchilega) on mudflats at low tide, Norfolk, UK. August

Sue Daly / Sand Mason Worm (Lanice conchilega). Channel Islands, UK, May.

Brent Stephenson / Sanderling (Calidris alba) pulling a large worm from sand. Taiohae, Nuku Hiva, Marquesas, French Polynesia, October.

Laurie Campbell / Sand Mason Worm (Lanice conchilega) tube in sand on beach, Isle of Skye, Scotland, August

Sue Daly / Sand mason worms (Lanice conchilega) Bouley Bay, Jersey, Channel Islands, UK

Gary K. Smith / Casts of Sand mason worms (Lanice conchilega), Norfolk, UK

Constantinos Petrinos / Bobbit worm {Eunice sp} large predatory polychaete Anilao, Batangas, Philippines

Benjamin Olson / Sanderling (Calidris alba) pulling worm out of sand, San Diego National Wildlife Refuge, California

Marc Robillard / Human footprint, and tracks of bird and worm activity in sand

Jacob Guy / Blackfin snake eel (Ophichthus altipennis) head above sand. The animal is waiting for prey to pass over. The rest of its body is buried beneath the sand. Lembeh Strait, Indonesia.

Roger Powell / Eurasian curlew (Numenius arquata) catching Lugworm (Arenicola marina). Lindisfarne National Nature Reserve, Northumberland, UK. January.

Joel Sartore / Photo Ark / Two Sand disc bryozoans (Discoporella doma), one with a Calcareus tube worm (Hydroides crucigera) and Encrusting sand tube worm (Sabellaria sp.) sheltering inside, Gulf Specimen Marine Lab and Aquariu...

Joel Sartore / Photo Ark / Two Sand disc bryozoans (Discoporella doma), one with a Calcareus tube worm (Hydroides crucigera) and Encrusting sand tube worm (Sabellaria sp.) sheltering inside, Gulf Specimen Marine Lab and Aquariu...

Joel Sartore / Photo Ark / Encrusting sand tube worm (Sabellaria sp.) and Ivory barnacles (Balanus eburneus) on the shell of a American / Common oyster (Crassostrea virginica), Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Encrusting sand tube worm (Sabellaria sp.) and Ivory barnacles (Balanus eburneus) on the shell of a North America / Common oyster (Crassostrea virginica), Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Blood clam (Noetia ponderosa) living on an old Florida fighting conch shell (Strombus alatus) shell. The pink is an encrusting bryozoan with an Encrusting sand tube worm (Sabellaria sp.) on the left,...

Joel Sartore / Photo Ark / Blood clam (Noetia ponderosa) living on an old Florida fighting conch shell (Strombus alatus) shell. The pink is an encrusting bryozoan with an Encrusting sand tube worm (Sabellaria sp.) on the left,...

David Fleetham / Reptilian snake eel (Brachysomophis henshawi) half buried in sand, hiding, Hawaii.

Alex Mustard / Portrait of a Black saddle snake eel (Ophichthus cephalozona) emerging from the sand at night. Dauin, Dauin Marine Protected Area, Dumaguete, Negros, Philippines. Bohol Sea, tropical west Pacific Ocea...

Roger Powell / Bar-tailed fodwit (Limosa lapponica) in winter plumage bathed in winter sun and catching a Lugworm (Arenicola marina). Holy Island (Lindisfarne), Nothumberland, England, UK December.

Roger Powell / Bar-tailed godwit (Limosa lapponica) in winter plumage, feeding on a Lugworm (Arenicola marina). Holy Island (Lindisfarne), Nothumberland, England, UK December.

Nick Upton / Honeycomb worm reef (Sabellaria alveolata) with clustered tubes built of sand grains attached to boulders, exposed at low tide with the sea in the background, Dunraven Bay, Glamorgan, Wales, September...

Georgette Douwma / Filter feeding appendages of a Feather duster worm - Sabellidae, extending from the sand. Tulamben, Bali, Indonesia.