Calcareous algae and cyanobacteria

Algae is an informal term used to describe a broad group of simple organisms from the plant kingdom. The organisms included within this grouping are aquatic photosynthetic biota with an extensive range of life habits and forms. These organisms range from micron‐sized unicellular forms to giant seaweeds and kelps, which can grow to several metres long. Both benthic and planktonic modes of life are known and display a wide variety of life cycles