Alex Mustard / Thorny seahorse (Hippocampus histrix) gripping onto a sponge. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Shane Gross / Portrait of a Thorny seahorse (Hippocampus histrix) near Malapascua, Philippines.

Shane Gross / Thorny or spiny seahorse (Hippocampus histrix) portrait made off Anilao, Philippines.

Georgette Douwma / Mantel of Spiny oyster (Spondylus varius). Indonesia. Indo-West Pacific.

Alex Mustard / Hedgehog seahorse (Hippocampus spinosissimus) female moves over a sandy seabed. Dauin, Negros Island, Philippines. Bohol Sea, tropical west Pacific Ocean.

Jurgen Freund / Details of Thorny oyster (Spondylus varius) with "eyes" in its mantle edge near the shell, New Ireland, Papua New Guinea

David Fleetham / Thorny Oyster shell (Spondylus varians), Komodo, Indonesia.

Jouan & Rius / Thorny devil (Moloch horridus), Central Australia, Australia

Jeff Rotman / Thorny Sea Horses (Hippocampus histrix) on Alcyonarian coral (Dendronephthya sp.). Israel, Red Sea.

Richard Du Toit / Cape Weaver (Ploceus capensis) male perching on thorny branch, Garden Route National Park, South Africa

Michael & Patricia Fogden / Thorny Devil (Moloch horridus) in the desert near Ayers Rock, Uluru-Kata Tjuta National Park, Australia

Gerry Ellis / Thorny Devil (Moloch horridus) overhead view, native to the Central Desert, Western Australia

Mitsuaki Iwago / Thorny Devil (Moloch horridus) on sand, Australia

Mitsuaki Iwago / Thorny Devil (Moloch horridus) walking across sand, Australia

Bert Willaert / Thorny devil (Moloch horridus). Francois Peron National Park, Shark Bay, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus). Francois Peron National Park, Shark Bay, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus). Francois Peron National Park, Shark Bay, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus) on sand. Francois Peron National Park, Shark Bay, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus) on roadside with car passing. Kalbarri National Park, Western Australia. October 2019.

Bert Willaert / Thorny devil (Moloch horridus) portrait. Kalbarri National Park, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus) walking on stones. Kalbarri National Park, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus). Kalbarri National Park, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus) camouflaged against brown stones and earth, dorsal view. Kalbarri National Park, Western Australia. October.

Bert Willaert / Thorny devil (Moloch horridus). Kalbarri National Park, Western Australia. October.

Magnus Lundgren / Spiny / thorny seahorse (Hippocampus histrix) with blurred motion, Balayan Bay, off Anilao, Batangas, Philippines, Pacific Ocean Minimum fees apply.

Tui De Roy / Steep, broken lava covered in dense, thorny vegetation on the western slope of Wolf Volcano, where hybrid descendants of Pinta and Floreana tortoises are mixed within the Wolf tortoise population. Wol...

Sergio Hanquet / Blue starfish (Coscinasterias tenuispina) regenerating from single arm Tenerife, Canary Islands.

Sergio Hanquet / Blue starfish (Coscinasterias tenuispina) close up of arm with tube feet, Tenerife, Canary Islands.

Bruno D'Amicis / Aestivating Cuban tree snail (Polymita picta) in thorny vegetation near Maisi, Cuba.

Georgette Douwma / Thorny oyster (Spondylus varius), patterns and colours on mantle caused by Zooxanthellae. Derawan Islands, East Kalimantan, Indonesia.

Emanuele Biggi / A young thorny Acacia tree (Vachellia sp.) growing in rocky desert around Sossusvlei, at night with Milky Way, Namibia

Magnus Lundgren / Thorny seahorse (Hippocampus histrix) juvenile, riding sea grass, Anilao, Philippines. Minimum fees apply.

Magnus Lundgren / Thorny seahorse (Hippocampus histrix) juvenile, Balayan Bay, Luzon, the Philippines Minimum fees apply.

Fred Olivier / Wide-angle tracking shot of a Thorny devil (Moloch horridus) walking, Shark Bay, Western Australia, 2016.

Fred Olivier / Thorny devil (Moloch horridus) next to flowering Parakeelya (Calandrinia polyandra), Shark Bay, Western Australia.

Fred Olivier / Thorny devil (Moloch horridus)walking around flowering Parakeelya (Calandrinia polyandra), Shark Bay, Western Australia.

Fred Olivier / Thorny devil (Moloch horridus) walking, leaves frame, Shark Bay, Western Australia, 2016.

Fred Olivier / Close-up of a Thorny devil (Moloch horridus) looking around, Shark Bay, Western Australia

Fred Olivier / Rear view of a Thorny devil (Moloch horridus) walking, Shark Bay, Western Australia.

Fred Olivier / Rear view of a Thorny devil (Moloch horridus) walking, Shark Bay, Western Australia.

Fred Olivier / Thorny devil (Moloch horridus) walking, Shark Bay, Western Australia.

Pascal Kobeh / Giant moray (Gymnothorax javanicus), Variable thorny oyster (Spondylus varius) and Iridescent cardinalfish (Pristiapogon kallopterus). Moheli, Comoros.

Pascal Kobeh / Thorny seahorse (Hippocampus histrix). Flores Sea, Indonesia.

Georgette Douwma / Kaleidoscopic image of Thorny oyster (Spondylus varians) pattern on mantle. Ceby, Malapascua Island, Philippines.

Robin Chittenden / Stonechat (Saxicola torquatus) perched on thorny branch. Suffolk, England, UK. March.

Robin Chittenden / Great spotted cuckoo (Clamator glandarius) perched in thorny bush. Cyprus. April.

Robin Chittenden / Dartford warbler (Sylvia undata) perched on thorny Bramble branch. Suffolk, England, UK. March.

Pascal Kobeh / Thorny seahorses (Hippocampus histrix) in coral, Sulu Sea, Philippines.