Nick Upton / Common limpets (Patella vulgata) and Poli's stellate barnacles (Chthamalus stellatus) on rocks exposed at low tide. Kimmeridge, Dorset, England, UK. July.

Nick Upton / Green-leaf worm (Eulalia viridis) scavenging on rocks encrusted with Barnacles (Semibalanus balanoides). Treyarnon Bay, Cornwall, England, UK. September.

Robert Thompson / Dog whelk (Nucella lapillus) and Common barnacle (Semibalanus balanoides) on rock. Mill Quarter Bay, Killard Point National Nature Reserve, Strangford, County Down, Northern Ireland. February.

Robert Thompson / Painted top shell (Calliostoma zizyphinum) and Common barnacle (Semibalanus balanoides) on rock at edge of Strangford Lough. Mill Quarter Bay, Killard Point National Nature Reserve, Strangford, County...

Olga Kamenskaya / Barnacle (Balanus balanus) underwater, off the coast of Svalbard, Norway, September.

Nick Upton / Group of Dog whelks (Nucella lapillus) in an intertidal rock crevice among Acorn barnacles (Balanus perforatus) and Beadlet anemones (Actinia equina), Cornwall, UK, April.

Solvin Zankl / Giant barnacles (Austromegabalanus psittacus) Comau Fjord, Patagonia, Chile, Atlantic Ocean

Nick Upton / Common limpet (Patella vulgata) and young Acorn barnacles (Semibalanus balanoides) attached to rocks on seashore, north Cornwall, UK, September.

Nick Upton / Patches of Wart lichen (Verrucaria mucosa / Wahlenbergiella mucosa) growing on rocks exposed at low tide alongside young Acorn barnacles (Semibalanus balanoides), Millook Haven, Cornwall, UK, Septembe...

Alex Hyde / Barnacles (Chthamalus montagui) exposed at low tide. Isle of Skye, Scotland. UK. April.

Alex Hyde / Acorn barnacle (Semibalanus balanoides) growing on shell of Common Mussel (Mytilus edulis), Isle of Skye, Scotland, April.

Alex Hyde / Acorn barnacle (Semibalanus balanoides) Isle of Skye, Inner Hebrides, Scotland, UK. April.

Pascal Kobeh / Giant barnacles (Balanus nubilus), Alaska, USA, Gulf of Alaska. Pacific ocean.

Chris Mattison / A figure from Antony Gormley's 'Another Place' installation covered in barnacles, including the invasive Austrominius modestus. Crosby, Merseyside, UK, April 2014.

Chris Mattison / A figure from Antony Gormley's 'Another Place' installation covered in barnacles, including the invasive Austrominius modestus. Crosby, Merseyside, UK, April 2014.

Chris Mattison / A figure from Antony Gormley's 'Another Place' installation covered in barnacles, including the invasive Austrominius modestus. Crosby, Merseyside, UK, April 2014.

Chris Mattison / Invasive barnacles (Austrominius modestus) growing on a sculpture forming part of the installation 'Another Place' on the beach at Crosby, Merseyside, April.

Chris Mattison / Acorn barnacles (Balanus balanoides) in rockpool, Northumberland, England, UK, May.

Chris Mattison / Acorn barnacles (Balanus balanoides) in rockpool, Northumberland, England, UK, May.

Nick Upton / Dog whelk (Nucella lapillus), a predator of barnacles, on rocks encrusted with Common barnacles / Northern rock barnacles (Semibalanus balanoides) exposed at low tide, with seaweed, a rock pool and th...

Nick Upton / Group of Montagu's stellate barnacles (Chthamalus montagui) attached to rocks on seashore, Kimmeridge, Dorset, UK, UK, March.

Nick Upton / Common limpets (Patella vulgata) and Acorn barnacles (Balanus perforatus) attached to rocks exposed at low tide, Lyme Regis, Dorset, UK, April.

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 / Two Hooked mussels (Ischadium recurvum), one with an Ivory barnacle (Balanus eburneus) attached to shell, Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Hooked mussel (Ischadium recurvum) with an Ivory barnacle (Balanus eburneus) attached to shell, Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Sea whip barnacle (Balanus conopea galeatus) portrait, 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 / Cord grass barnacle (Chthamalus fragilis) on white background, Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Cord grass barnacle (Chthamalus fragilis) on black background, Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Ivory barnacles (Amphibalanus eburneus) filter feeding, Gulf Specimen Marine Lab. Captive.

Joel Sartore / Photo Ark / Ivory barnacles (Amphibalanus eburneus) filter feeding, Gulf Specimen Marine Lab. Captive.

Shane Gross / China rockfish (Sebastes nebulosus) resting among Giant acorn barnacles (Balanus nubilus), Browning Pass, Queen Charlotte Strait, British Columbia, Canada

David Hall / Split level of Acorn barnacles (Balanus glandula) just below the surface, Seven Tree Island, Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Acorn barnacles (Semibalanus cariosus) and (Balanus glandula), Mussels (Mytilus sp.), and Plumose anemones (Metridium senile) underwater at high tide, Seven Tree Island, Browning Pass, Queen Charlotte...

David Hall / Pygmy rock crab (Cancer oregonensis) in the empty shell of a Giant Acorn Barnacle (Balanus nubilus). Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

Nick Upton / Acorn barnacles (Balanus perforatus) filter feeding underwater in a rock pool, Rhossili, Gower Peninsula, Glamorgan, Wales, UK, August.

Nick Upton / Acorn barnacles (Balanus perforatus) filter feeding underwater in a rock pool, Rhossili, Gower Peninsula, Glamorgan, Wales, UK, August.