magnetosome
/maɡˈniːtə(ʊ)ˌsəʊm/Biology
noun
Any of the intracellular, membrane-bound crystals of the iron oxide magnetite (or, rarely, of an iron sulphide such as greigite) found, usually arranged in a chain, in magnetotactic bacteria and certain other magnetotactic organisms.
Origin
1980s. From magneto- + -some.