magnetofossils are not only being studied for their paleoenvironmental or paleoclimatic indicators. as mentioned above, magnetofossils hold a remanent magnetization when they are formed. that is, the magnetite (or greigite) aligns in the direction of the geomagnetic field. the magnetite crystals can be thought of as being a simple magnet with a north and south pole, this north-south orientation aligns with the north-south magnetic poles of the earth. these fossils are then buried within the rock record. researchers can examine these rock samples in a remanent magnetometer where the effects of earth's current magnetic field is removed, to determine the remanent, or initial, magnetization of the rock sample when it was formed. in knowing the orientation of the rock in-situ and the remanent magnetization, researchers can determine the earth's geomagnetic field at the time the rock was formed. this can be used as an indicator of magnetic field direction, or reversals in the earth's magnetic field, where the earth's north and south magnetic poles switch (which happen on average every 450,000 years).