Magnetotactic Bacteria

Blakemore (1975) first documented magnetotactic bacteria and found that the microorganisms synthesize chains of nano-sized magnetic particles that function as a compass needle. This "nano-compass" allows the microbe to passively orient itself in Earth's geomagnetic field . These magnetic nanoparticles are synthesized by a specific set of proteins that are contained within membrane-bound organelles called magnetosomes. Each bacterium contains 10–20 magnetosomes, each of which contains a magnetic nanoparticle. The magnetosomes are aligned in a chain-like fashion, which impart a magnetic dipole to the bacterial cell and allows the cells to "sense" Earth's geomagnetic field . 

These prokaryotic Microoganisms are found in freshwater and marine habitats. They are all anaerobes and prefer environments that contains little of oxygen .

Magneto taxis is the process by which magnetotactic bacteria orientate themselves within Earth's geomagnetic field and then use their flagellum to swim to oxygen-poor sediments where the oxygen and redox conditions preferred by these organisms are found.

Today, they are used to distribute drugs to the tumours in human body by operating them with a magnetic machine to give them directions. They use as drug distributors because as still tumour drugs are injected in human body they destroy tumours but they also destroy other things of body which is known as side effects of drugs. Still this process is in research, i hope in few years they are used in hospitals all around the world .