Like the Archaea, Eubacteria are prokaryotic cells. Their membranes on the other hand are made out of unbranched fatty acids chains attached to glycerol by ester linkages. Two of the best examples of bacteria are Cyanobacteria and mycoplasmas. Unlike the Archaea they don't have containing linkages, they are grouped into separate and different categories and hence a different domain. There is a lot of diversity in this domain, making it almost impossible to know how many species of bacteria exist on the planet.