Both of those are actually common enough that if a biological ecosystem ever discovered a competitive advantage for very powerful magnetic crystals, it might ha

Both of those are actually common enough that if a biological ecosystem ever discovered a competitive advantage for very powerful magnetic crystals, it might have come up with Fe16N2 instead of just the magnetite (Fe3O4) and greigite (Fe3S4) that currently form the basis of biological magnetism. https://en.wikipedia.org/wiki/Magnetosome https://en.wikipedia.org/wiki/Magnetosome