Archaebacteria is the subkingdom of Bacteria. It is single-celled and has no nucleus. Archaea is similar to Bacteria in size and shape but can survive more extreme conditions. Their habitats can vary from the human stomach to salt lakes to hot springs. It was seperated from Bacteria and classified as it's own prokaryote in 1977 by Carl Woese. Most Archaea have a cell wall but lack peptidoglycan, a plasma membrane that Bacteria has. Depending on the species of Archaebacteria, some may gain nutrients from inorganic compounds, like sulfur, and some may be phototrophs (sunlight ---> food). Though they are phototrophs, these organisms cannot make oxygen from the sunlight they take in. They reproduce asexually by binary or multiple fission, fragmentation, or budding. When the cell reproduces, it has the same genetic make up of the parent cell. They aren't necessarily harmful or helpful.