Magnetotactic bacteria, being aquatic prokaryotes, are diverse with respect to phylogeny, physiology, and morphology. They are motile, polyphyletic, and they can be studied by molecular methods in the laboratory. They are similar to the non-magnetic, photosynthetic, nonsulfur purple bacteria. The formation of magnetic-sensitive inclusions are induced by incubation in iron rich medium in some species of nonmagnetotactic photosynthetic purple bacteria. There are a number of types of magnetotactic bacteria, one of the most unusual morphological types of which is a marine, greigite forming multicellular magnetotactic prokaryote. They are made of a compact assembly of flagellated cells that perform a coordinate biomineralization and magnetotactic motility. In terms of application, Magnetotactic bacteria can be applied to isolated magnetosome crystals, as well as in entire living cells. In addition, there have been suggestions that they can be used for magnetic domain analysis in magnetic materials at the microscopic scale.