Growth of chiton teeth evidenced from magnetic measurement and microstructure characterization

The evolution of the growth of chiton teeth was elucidated by transmission electron microscopy and magnetic measurements. The deposition of iron minerals starts from the seventh row of the radula, beginning as amorphous aggregates, gradually changes shape and aggregation state, and finally crystallizes to lepidocrocite at the anterior side and magnetite at the posterior side of the radula. From magnetic measurements, it is postulated that magnetite crystallizes to single-domain particles with measurable magnetization at around the 20th tooth and increases rapidly. The quantity of magnetite in the minerals can be calculated from the magnetization data. A maximum of 29 wt.% has been measured at around the 36th tooth, and the amount then decreases, probably due to wearing-out of the magnetite