Robin Chittenden / Golden Star Tunicate (Botryllus schlosseri) Norfolk UK, November

Franco Banfi / Two Red sea-squirts (Halocynthia papillosa) Santa Teresa, Sardinia, Italy, Tyrrhenian Sea, Mediterranean,

Georgette Douwma / Valentine's puffer (Canthigaster valentini) with Golden sea squirts (Polycarpa aurata) Lembeh, Sulawesi, Indonesia.

Georgette Douwma / Sea squirts: Golden sea squirt (Polycarpa aurata) and Blue club tunicate (Rhopalaea crassa) Lembeh, Sulawesi, Indonesia.

Franco Banfi / Pacific sea peach (Halocynthia aurantium) Vancouver Island, British Columbia, Canada, Pacific Ocean

Constantinos Petrinos / Chromodorid nudibranch (Chromodoris annae) on Sea Squirt (Polycarpa aurata) Lembeh Strait, North Sulawesi, Indonesia.

Sue Daly / Star ascidian (Botryllus schlosseri) L'Etac, Sark, British Channel Islands.

Alex Mustard / Slender sapsucking slug (Thuridilla gracilis) on surface of Royal seasquirt (Polycarpa aurata) Aljui Bay, Waigeo Island, Raja Ampat, West Papua, Indonesia. Tropical West Pacific Ocean.

Solvin Zankl / Rich reef landscape with Ox heart ascidian (Polycarpa aurata) and Reef fish, Raja Ampat, West Papua, Indonesia, Pacific Ocean.

Solvin Zankl / Ox heart ascidian (Polycarpa aurata) Raja Ampat, West Papua, Indonesia, Pacific Ocean.

Franco Banfi / Red sea-squirt (Halocynthia papillosa) Ischia Island, Italy, Tyrrhenian Sea, Mediterranean

Franco Banfi / Couple of Red sea-squirt (Halocynthia papillosa) Ischia Island, Italy, Tyrrhenian Sea, Mediterranean