• No Peptidoglycan: Unlike other bacteria, the cell walls of archaebacteria lack peptidoglycan. Instead, they contain specialized proteins, glycoproteins, or a substance called pseudomurein (pseudopeptidoglycan).

• Survival in Extremes: This unique cell wall structure, along with specialized membrane lipids (ether-linked instead of ester-linked), is what allows archaebacteria to survive in extreme environments such as hot springs (thermophiles), salty areas (halophiles), and marshy habitats (methanogens).