SINCLAIR STAMMERS / Timelapse of filaments of Oscillatoria, a type of Blue green algae gliding over each other, filmed using differential interference contrast.

Andres M. Dominguez / Dove's-foot crane's-bill leaf (Geranium molle) and algae in ice with air bubbles, Sierra de Grazalema Natural Park, southern Spain, February.

Jeff Vanuga / Ephydrid flies (Ephydra sp) that eat microscopic algae and survives during the winter in thermal pools. Biscut Basin, Yellowstone National Park, Wyoming, USA, January.

Alex Hyde / Chlorophyte or green alga (Volvox aureus) in pond water. UK. The larger spheres are approximately 0.5mm in diameter. Digital composite image.

Jan Hamrsky,Jan Hamrsky / Trumpet animalcules (Stentor polymorphus) with algal symbionts (Chlorella), Europe, controlled conditions

Juan Carlos Munoz,Juan Carlos Munoz / Lesser flamingo flock (Phoeniconaias) flying over lake with green algae, aerial view, Rift valley, Kenya

Graham Eaton / Split level shot of Llyn Idwal and Cwm Idwal, showing freshwater habitat with Green lacustrine algae (Chlorophyceae sp.), Snowdonia NP, Gwynedd, Wales, UK, August

Roberto Rinaldi / Yellow fan coral / Seafan (Paramuricea clavata) amongst mass of invasive algae (Caulerpa taxifolia) with Rainbow wrasse fish (Coris julis), Strait of Messina, Southern Italy

Alex Mustard / 2020VISION / Tufts of seaweed growing on a shallow seabed, Island of Coll, Inner Hebrides, Scotland, UK, June

Alex Mustard / 2020VISION / Meadow of seaweeds in a shallow channel between islands in the Cairns Of Coll, Island of Coll, Inner Hebrides, Scotland, UK, July

Juergen Freund / Mermaid's wineglass algae (Acetabularia calyculus) Batangas, Philippines.

Juergen Freund / Aerial view of a seaweed farmer tending his crop, growing agar-agar for processing into carageenan (gelatinous extracts used as binder for food or product) Philippines, May 2009.