Pascal Kobeh / Halimeda ghost pipefish (Solenostomus halimeda), two mimicking Cactus algae (Halimeda sp), feeding above sea floor. Flores Sea, Indonesia.

Pascal Kobeh / Halimeda ghost pipefish (Solenostomus halimeda) mimicking the halimeda algae. Sulu sea, Philippines

Georgette Douwma / Banggai cardinalfish (Pterapogon kauderni) with Green algae (Halimeda copiosa). Lembeh Strait, North Sulawesi, Indonesia.

Georgette Douwma / Funnelweed (Padina gymnospora) and Green Algae (Halimeda sp.). West Papua, Indonesia. Indo-West Pacific.

Georgette Douwma / Green algae (Halimeda opuntia). North Sulawesi, Indonesia.

David Fleetham / Red encrusting sponge (Clathria sp) on calcium carbonate-producing Seaweed / Green algae (Halimeda kanaloana). Hawaii.

David Fleetham / Opisthobranch (Melibe engeli) swimming, commonly found in beds of calcarious algae (Halimeda kanaloana) in Hawaii.

Linda Pitkin / Spotted Seahorse (Hippocampus taeniopterus), resting in patch of green algae (Halimeda) Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Cactus coralline macroalgae (Halimeda sp) on seabed, Bunaken island, Sulawesi, Indonesia, Indo-pacific.

Alex Mustard / A Halimeda Ghost Pipefish (Solenostomus halimeda) on a coral reef. Lembeh Strait, Sulawesi, Indonesia. Celebes Sea.

Juergen Freund / Sample of Green algae {Halimeda sp} from Coral Reef census, Lizard Island, Queensland, Australia, April 2008. To store the algae, specimens are pressed and dried out in a herbarium press, this simple...

Chris Newbert / Spider Crab (Majidae) covered in Sponges, on Halimeda Algae (Halimeda macroloba) 60 feet deep, Papua New Guinea

Chris Newbert / Cuttlefish (Sepia sp) clinging to Algae (Halimeda macroloba) 50 feet deep, Papua New Guinea

Chris Newbert / Crab (Huenia sp) carrying Algae (Halimeda macroloba) for camouflage, 70 feet deep, Papua New Guinea

Chris Newbert / Goby group in Algae (Halimeda macroloba), 90 feet deep, Solomon Islands

Birgitte Wilms / Diamond Leatherjacket (Acreichthys tomentosus) in Algae (Halimeda sp) 10 feet deep, Papua New Guinea

Chris Newbert / Goby (Pleurosicya sp) on Algae (Halimeda sp) 20 feet deep

Chris Newbert / Seahorse (Hippocampus sp) hiding in Algae (Halimeda sp) 20 feet deep, Papua New Guinea

David Fleetham / Common reef / Day octopus (Octopus cyanea) hiding on the seabed in calcareous halimeda algae (Halimeda opuntia), Hawaii.

David Fleetham / Spiny cowfish / Roundbelly trunkfish (Lactoria diaphana), amongst calcareous halimeda algae (Halimeda opuntia), Hawaii.

Etienne Littlefair / Halimdea ghost pipefish (Solenostomus halimeda) swimming over coral reef, Great Barrier Reef, Australia.

Fred Bavendam / Blue-ringed octopus (Hapalochlaena sp.) clinging on to branch of Halimeda seaweed (Halimeda sp.), Milne Bay, Papua New Guinea, Pacific Ocean.

Georgette Douwma / Shortfin lionfish (Dendrochirus brachypterus) next to green algae (Halimeda copiosa). Lembeh Strait, North Sulawesi, indonesia.

Georgette Douwma / Green algae (Halimeda sp). Derawan Islands, East Kalimantan, Indoneisa.