when an organism dies the magnetosomes become trapped in sediments. under the right conditions, primarily if the redox conditions are correct, the magnetite can then be fossilized and therefore stored in the sedimentary record. the fossilization of the magnetite (magnetofossils) within sediments contributes largely to the natural remanent magnetization of the sediment layers. the natural remanent magnetization is the permanent magnetism remaining in a rock or sediment after it has formed.