“…(a) Biogenic magnetite nanoparticles synthesized by magnetotactic bacteria (MTB; Bazylinski & Frankel, 2004) and their fossil remains in the geological records (i.e., magnetofossils; Kopp & Kirschvink, 2008) have diverse crystal shapes and chain structures indicative of key paleoenvironmental signals (e.g., Amor et al., 2022; Berndt et al., 2020; Chang et al., 2019, 2018; Yamazaki & Kawahata, 1998). (b) Silicate‐hosted magnetic nanoparticle inclusions carrying important paleomagnetic signals (e.g., Tarduno et al., 2006, 2010) have variable morphologies and complex microstructures (Chang et al., 2016; Nikolaisen et al., 2020, 2022). (c) Tetrataenite in meteorites, which can record the magnetic activity of planetesimals in the early solar system (Bryson et al., 2014, 2015), has a variety of particle shapes and its particle size correlates with the metallographic cooling rate of meteorites (Einsle et al., 2018; Goldstein et al., 2009; Yang et al., 2010).…”