»Algae /Wikipedia/
»Introduction to the Green Algae /Berkeley/
ξ vary from small, single-celled forms to complex multicellular forms
ξ the giant kelps of the eastern Pacific grow to more than 60 meters in length and form dense marine forests
ξ seaweeds are marine algae
ξ simple organisms composed of one cell, or grouped together in colonies, or as organisms with many cells,
ξ sometimes collaborating together as simple tissues
ξ Algae ("al'guy" or "al'gay") is the plural; Alga ("al'ga") is the singular
ξ Algae of one kind or another have been around for more than 2 billion years
ξ from unicellular and 3-10 µm (microns) to giant kelps up to 70 meters long and growing at up to 50 cm per day
ξ found in mostly aquatic situations (need water to reproduce and, generally, to photosynthesise)
ξ about 30,000 species of algae