Radiolaria are marine protozoa that have thrived in the world's oceans for millions of years. They are particularly unique among marine plankton in that they build silica skeletons, which have allowed them to be preserved in the fossil record. These skeletons are ornate and complex and often demonstrate perfect geometric form and symmetry. The complex and beautiful glass-like structures are visually interesting when examined with electron microscopy. These attributes, coupled with their availability, size, ease of mounting and preparation make them superb specimens for introducing students to the use of electron microscopy (EM).