School gap
English textbooks added archaea late. If you only learned bacteria vs everything else, this topic is the missing third.
Climate English now names methane from cattle and wetlands. Some of that methane is archaeal metabolism, not a cartoon volcano microbe.
You will not find archaea on a yogurt label. The local lesson is vocabulary: domain, membrane lipids, and why Gram stain was never meant for them.
Local notes
Methane talk
Public climate copy names cows and rice paddies. Archaea are part of that chemistry.
Not a kitchen culture
Do not hunt archaea in home fermentation. This is a tree-of-life page.
Official pages own schedules and treatment. This atlas does not.
More in Tree of microbes
Bacteria
Single-celled prokaryotes with cell walls — the oldest widespread life form, and both partners and pathogens.
Familiarity 95Viruses
Packets of DNA or RNA that are not cells — they replicate only inside living hosts.
Familiarity 96Fungi
A eukaryotic kingdom of yeasts, moulds and mushrooms — chitin walls, external digestion, partners of plants.
Familiarity 80Bacteriophages
Viruses that infect bacteria — Earth's most abundant biological entities, and a concept-level idea in medicine.
Familiarity 42Protozoa
Motile unicellular eukaryotes — a teaching grade that includes pond ciliates and a minority of serious parasites.
Familiarity 58