1. Introduction; 2. Biomineralization, Structure and Biogeochemistry of the Echinoderm Skeleton; 3. Stereom Types and Relationship to Phylogeny, Growth Rate and Investing Soft Tissues; 4. Stereom of Fossil Echinoderms – Preservation Style and Observational Methods; 5. Stereom Microstructure – A Powerful Tool for Assessing the Paleobiology and Paleoecology of Fossil Echinoderms; 6. Conclusions.