Radular teeth of chitons were studied by using magnetic torque-meter and tr
ansmission electron microscopy (TEM). The magnetic torque curves give clear
evidence of presence of strong uni-axial magnetic anisotropy. The easy axi
s is along the length direction of tongue-like radula. The TEM pattern show
s that long chip-like magnetite nano-scaled particles packed in the radular
teeth with both uni-axial shape anisotropy and magneto-crystalline anisotr
opy.