Think life is simple. “Yes,” you say – “those with nucleus are eukaryotes, and those without are bacteria.” But, not so fast. A domain of single cell organisms that used to be called archaebacteria is now a whole new branch in the tree of life. We now give it its own name, “Archae”. Archae posses properties that separate them from bacteria and higher life forms. What makes Archae different? Their living conditions, energy sources and cell membrane lipids make them unique.