Jaymi Heimbuch / Leaf Barnacle (Pollicipes polymerus) group, California Mussels (Mytilus californianus), and White Acorn Barnacles (Balanus glandula), Lincoln City, Oregon

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

Doc White / Humpback whale (Megaptera novaeangliae) with two kinds of barnacles, the long Gooseneck barnacle (Conchoderma aurtium) which lives on the Acorn barnacle (Coronula diadema) also whale lice, (Cyamus boo...

Tony Wu / Southern Humpback whale (Megaptera novaeangliae australis) dorsal fin detail with Acorn barnacles (Coronula diadema) and whale lice (Cyamus boopis) visible, South Africa

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...