Microbial Motile Structures (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption The motile structures in Bacteria and Archaea: the archaellum (center) functions like a bacterial flagellum but its structure resembles a bacterial Type IV pilus. Credit Sonja-Verena Albers of the MacPlanck Institute of Terrestrial Microbiology Usage Restrictions with credit as given 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.