Algae belong to many distinct evolutionary lineages and are not a single cohesive group. They are typically simple, aquatic, autotrophic organisms - meaning they photosynthesise simple inorganic sources into complex organic nutritive compounds. They are photosynthetic like vascular plants and are responsible for 50% of the oxygen produced globally - every second breath you breathe is produced by algae. Algae range from unicellular to multicellular forms with seaweeds (macro algae) being the largest and most complex marine forms.
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