Nick Upton / Frosty sea mat (Electra pilosa) bryozoan colony growing on frond of Dulse (Palmaria palmata) red alga exposed on a low spring tide. Rhossili, The Gower Peninsula, UK, July.

Nick Upton / Close up of Frosty sea mat (Electra pilosa) bryozoan colony growing on frond of Dulse (Palmaria palmata) red alga exposed on a low spring tide. Rhossili, The Gower Peninsula, UK, July.

Nick Upton / Spiral egg ribbon of a sea slug (probably Haminoea navicula) attached to a boulder in a rockpool alongside Star ascidians (Botryllus schlosseri), Bryozoans, Barnacles and Red algae low on the shore, H...

Nick Upton / Four Sea squirts (Ascidiella scabra) attached to boulder in a rockpool alongside serpulid worm tubes, Bryozoans, Barnacles and Red algae low on the shore, Helford River, Cornwall, UK, August.

Nick Upton / Four Sea squirts (Ascidiella scabra) attached to boulder in a rockpool alongside serpulid worm tubes, Star ascidians, Bryozoans, Barnacles and Red algae low on the shore, Helford River, Cornwall, UK,...

Nick Upton / Star ascidian (Botryllus schlosseri), a colonial sea squirt growing on rocks exposed on a low spring tide among barnacles, bryozoans and red algae, North Berwick, East Lothian, UK, July.

Nick Upton / Sea mat (Alcyonidium diaphanum), a colonial bryozoan, growing on rocks exposed on a low spring tide, North Berwick, East Lothian, UK, July.

Nick Upton / Sea mat (Alcyonidium diaphanum), a colonial bryozoan, growing on rocks exposed on a low spring tide alongside red algae, North Berwick, East Lothian, UK, July.

Sue Daly / Finger Bryozoan / Sea Mat (Alcyonidium diaphanum). Channel Islands, UK, June.

Sue Daly / Potato Crisp Bryozoan (Pentapora foliacea / fascialis) and Staghorn Sponge (Axinella dissimilis). Channel Islands, UK, July.

Sue Daly / Frosty Sea Mat Bryozoan (Electra pilosa). Channel Islands, UK, August.

Sue Daly / Potato Crisp Bryozoan / Ross Coral (Pentapora foliacea / fascialis). Channel Islands, UK, June.