Nudibranch on coral, Papua New Guinea, Pacific

Sabellaria alveolata honeycomb worm reef, Mimid beach, Sidi Boufdail, Mirleft, Morocco, North Africa, Africa

Rock formations and reflection, Tungeneset, Senja, Norway, Scandinavia, Europe

Algae on an ice block, Baffin island, Nunavut, Canadian Arctic, Canada, North America

Vibrant pink water lily blooming in a tranquil pond with green algae and lily pads, reflecting serene beauty in nature at Kew Gardens, London, England, United Kingdom, Europe

A pool coloured red from algae that have been fertilized by seabird guano on the Farne Islands, Northumberland, UK.

Green algae and yellow lichen on the Farne Islands, Northumberland, UK.

footballer sweep (neatypus obliquus) diagonal yellow bands are edged in black and stand out against the silvery-blue body, wild, day, marine protected area, reef, in small schools diving off Rottnest Island, Western Australia, Indian Ocean. MORE INFO: other name stripey, eating green algae as they sweep over the reef.

Black Opal Pool, Hot Spring, Yellow Algae and Mineral Deposits, Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Rainbow and Cascade Terrace, Orakei Korako Cave and Thermal Park, Taupo-Rotorua, North Island, New Zealand

Yellow bacteria and algae in a hot spring at Black Sand Basin and Biscuit Basin, Yellowstone National Park, Wyoming, USA, North America

Rainbow and Cascade Terrace, Orakei Korako Cave and Thermal Park, Taupo-Rotorua, North Island, New Zealand

Fjord landscape with small rock islands at low tide with yellow seaweed, small wooden boat between archipelagos in the sea, Lodingen, Nordland, Lofoten, Norway, Europe

Hawaii, Goldring surgeonfish and yellow tangs are cleaning algae from the shell of this green sea turtle (Chelonia mydas) an endangered species.

Mouth detail of a colourful and healthy Mushroom coral, Fungia fungites, that is growing on a tropical coral reef in the Philippines. Mushroom coral is unique in the coral world, in that it does not attach itself to the bottom, Philippines

Mouth detail of a colorful and healthy mushroom coral (Fungia fungites) that is growing on a tropical coral reef. Mushroom coral is unique in the coral world, in that it does not attach itself to the bottom, Philippines

Clay loaded with iron oxides and dried out, Rio Tinto, Andalusia, Spain *** Local Caption *** R?o Tinto ("Red River") is very acidic (Ph 2) and has a deep reddish hue due to iron dissolved in water. The acidity of the watercourse is linked to the drainage of pyrite, which is very present in the subsoil. Extremophilic and endemic bacteria and algae colonize the river bed, forming a fragile biofilm that evokes the hot springs of Yellowstone Park in the USA.