Membrane Structure (IMAGE) University of Washington Caption The archaea have a lipid molecule in their membrane that can vary slightly in its structure. At the bottom are two forms of this lipid with five rings of carbon, which are more common when the archaea grows in colder water. The new study finds the membrane lipid structure also shifts in low-oxygen water. Credit A. Ingalls / University of Washington Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.