Methanogens belong to

Methanogens are one of the groups of archaebacteria present either in marshy places or in the rumen of cattle. They are involved in methane or biogas production. They have special cell wall structure, which is made of pseudomureins.

(1) Eubacteria are not involved in methane production and they have peptidoglycan in their cell wall.

(2) Dinofl agellates are motile and usually photosynthetic protists. They have two flagella, are primarily aquatic and they have cell wall made of cellulosic plates. 

(3) Slime moulds are fungi-like or saprophytic protists, which thrive on dead, decaying organic matter.