magnetotactic bacteria use iron to create magnetite in magnetosomes. as a result of this process, increased iron levels correlate with increased production of magnetotactic bacteria. increases in iron levels have been long associated with hyperthermal (period of warming, usually between 4-8 degrees celsius) periods in the earth's history. these hyperthermal events, such as the palaeocene-eocene thermal maximum or the holocene warm period (hwp), stimulated increased productivity in planktonic and benthic foraminifera, which in turn, resulted in higher levels of sedimentation. furthermore, an increase in temperature (like the one in the hwp) may also be associated with a wet period. these warm and wet conditions were favourable for magnetofossil production due to an increased nutrient supply in a period of post-glacial warming during the hwp. as a result, this period shows an increase in magnetofossil concentration. using this increase in concentration, researchers can use magnetofossils as an indicator of a period of relatively high (or low) temperatures in earth's history. dating of these rocks can provide information about the time period of this climate change and can be correlated to other rock formations or depositional environments in which the earth's climate at that time may not have been as clear. sediment aging and dissolution or alteration of magnetite present problems with providing useful measurements as the crystals structural integrity may not be preserved.