Although these marine Methanobacteriati are difficult to culture and study in a lab, genomic sequencing suggests that they are motile heterotrophs.

[9] Some Methanobacteriati are highly adaptable; an order called Halobacteriales are usually found in extremely salty and sulfur-rich environments but can also grow in salt concentrations as low as that of seawater 2.5%.

[5] The LPSN, which aligns itself with the Code, adopts this view and[10] lists the earlier Methanobacteriati as a invalidly published phylum.

[15] The taxon Methanobacteriati is also listed in the Bergey's Manual of Systematics of Archaea and Bacteria, but this is because the latest version of the chapter was published in 2017.

Thermococci Hadesarchaea Methanobacteria Methanopyri Methanococci Thermoplasmata Archaeoglobi Methanomicrobia "Nanohaloarchaeota" Haloarchaea "Altiarchaeota" Diapherotrites Micrarchaeota Undinarchaeota Aenigmarchaeota Nanoarchaeota Parvarchaeota Mamarchaeota Pacearchaeota Woesearchaeota

Lokiarchaeota Odinarchaeota Thorarchaeota Heimdallarchaeota Eukaryota "Undinarchaeota" "Huberarchaeaota" "Aenigmarchaeota" "Nanohalarchaeota" Nanobdellota "Altarchaeota" "Iainarchaeota" "Micrarchaeota" "Methanococcia" "Hadarchaeia" "Thermococcia" "Hydrothermarchaeia" "Methanopyria" "Methanobacteriia" "Izemarchaea" (MBG-D, E2) "Poseidoniia" (MGII & MGIII)[28] "Thermoplasmatia" "Methanomicrobia" "Methanoliparia" "Archaeoglobia" "Syntropharchaeia" Methanocellia Methanosarcinia Methanonatronarchaeia Halobacteria Promethearchaeota Thermoproteota