Microscopic single-celled algae with intricate glass-like cell walls made of silica. These photosynthetic organisms are major producers of oxygen and form the base of many aquatic food webs.
From Greek 'diatomos' meaning 'cut in half', referring to their cell walls that consist of two overlapping halves like a pillbox. The term was coined in the early 19th century when microscopes first revealed their structure.
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