Center: Colored scanning electron micrograph of phycobionts of Evernia prunastri adsorbed on bioskin. See article by Blanch et al. in this issue pp 89–92. Micrograph by M. T. Solas, Department of Cell Biology, School of Biology, Complutense University of Madrid Spain. (Magnification, ca. 5000×)

Upper left: Transmission electron micrograph of bacteriophage Ø29. Negative staining with uranyl acetate. From Margarita Salas, Center for Molecular Biology "Severo Ochoa", CSIC-UAM, Madrid, Spain. (Magnification, ca. 200,000×)

Upper right: Scanning electron micrograph of square haloarchaea observed in Santa Pola, Alicante, Spain, solar salterns. Micrograph by Silvia González-Acinas and Josefa Antón, University Miguel Hernández, Alicante, Spain. (Magnification, ca. 25,000×)

Lower left: Transmission electron micrograph of Ostreococcus tauri in division. This protist, the smallest known free eukaryotic cell, was identified by C. Courties and M.-J. Chrétiennot-Dinet in Thau Lagoon, France, in 1995. Micrograph by the same authors, from Arago Laboratory, CNRS, Banyuls-sur-Mer, France. Diameter of the dividing cell 1.2 µm (Magnification, ca. 70,000×)

Lower right: Micrograph of several Dematiaceus fungi hyphae from Rio Tinto, Spain. They are acidophilic and resistant to several heavy metals. Micrograph by Ricardo Amils and Anabel López-Archilla, Autonomous University of Madrid, Spain. (Magnification, ca. 400×)