All organisms in the kingdom Archaebacteria classify as unicellular. Archaebacteria form some of the most basic but highly structured life forms on Earth. They share many commonalities with closely-related Eubacteria, such as a complex physical design and the ability to perform all life functions using just one cell.
The kingdom of Archaebacteria contains some of the hardiest and most resilient creatures in the world. Archaebacteria thrive in conditions considered inhospitable by many life forms, such as scorching deserts and the Arctic tundra. These bacteria belong to a large global population. They exist on land and at sea, and appear in virtually every region of Earth. These organisms classify as prokaryotes, which means that their cells lack a nucleus and defined structure. Their cells also lack membrane-bound organelles, which typically perform special duties in more complex organisms.
In addition to bacteria, Archae refers to other prokaryotes and some eukaryotes. The distinction between these tiny organisms often causes confusion in the field of biology, leading to continuing controversy and differing opinions regarding the classification of these similar species. Archae reproduce using asexual reproduction, which is carried out through binary fission, fragmentation and budding. Unlike many other asexual organisms, archae do not reproduce using spores. They classify as extremophiles, meaning they inhabit areas that support few, if any, other life forms.