This comprehensive book highlights the importance of Cyanidioschyzon merolae (C. merolae), an ultrasmall unicellular red alga, as a model eukaryote organism. The chapters introduce recent studies on C. merolae, from culture, synchronization and isolation methods of nucleic acids, proteins and organelles for molecular biological and cytological analyses, as well as its application in genetic engineering of environmental—stress—tolerant crops and oil production. In addition to discussing recent advances based on the complete genome information and molecular biological techniques such as genetic modifications and bioinformatics, the book includes visualization aids demonstrating that both classical and recent imaging techniques of fluorescent and electron microscopy can be applied to analyses of C. merolae. This publication offers a definitive resource for both beginners and professionals studying C. merolae, particularly in the field of molecular biology, evolutionary biology, morphology, biochemistry and cell biology, as well as those interested in its applications in medical sciences and agriculture.