Sue Daly / Nudibranch (Flabellina gracilis) feeding on bryozoan (Membranipora membranacea), Trondheimsfjord, Norway, July.

Solvin Zankl / Kelp membranipora bryazoan (Membranipora isabelleana) Comau Fjord, Chile, January.

Sue Daly / Nudibranch (Polycera quadrilineata) feeding on bryozoan Sea mat (Membranipora membranacea) St Abbs Voluntary Marine Reserve, Scotland (North Sea).

Sue Daly / Ross Bryozoan (Pentapora fascialis) L'Etac, Sark, British Channel Islands.

Alex Mustard / Nudibranch (Adalaria jannae) with egg masses laid on the bryozoan (Membranipora sp.), which is growing on a kelp frond. Browning Pass, Vancouver Island, British Columbia, Canada. North East Pacific Oc...

Lewis Jefferies / Common hermit crab (Pagurus bernhardus) in Painted topshell, resting on Golden kelp (Laminaria ochroleuca) frond, encrusted with Lacy crust bryozoans (Membranipora membranacea), Lizard Peninsula, Corn...

Lewis Jefferies / Spiney squat lobster (Galathea strigosa) resting at night on Golden kelp (Laminaria ochroleuca) frond covered in Seamat (Membranipora membranacea), Lizard Peninsula, Cornwall, UK, Atlantic Ocean.

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 / Wool bryozoan (Amathia convoluta) on white background, Gulf Specimen Marine Lab and Aquarium.

Joel Sartore / Photo Ark / Wool bryozoan (Amathia convoluta) on black background, Gulf Specimen Marine Lab and Aquarium.

Alex Mustard / Purple and pink Nudibranch (Edmundsella pedata), with mouth visible, crawling over Square-end hornwrack (Chartella papyracea), Swanage, Dorset, UK, English Channel.