Otoliths, CaCO<SUB>3</SUB> ear bones, are commonly used age and growth structures of fishes, and most are comprised of the densest CaCO<SUB>3</SUB> polymorph, aragonite. Sturgeon otoliths, in contrast, are purportedly the rare and structurally enigmatic polymorph, vaterite. Vaterite is an important material used in biomedical to personal care applications. While sturgeon otoliths are primarily composed of vaterite, they also contain calcite. For the vaterite fraction, neutron diffraction data provide enhanced discrimination of the carbonate group compared to x-ray diffraction data, owing to the different relative neutron scattering lengths, and offer the opportunity to uniquely test the various crystal structural models proposed for vaterite. Of those, space group <I>P</I>6<SUB>5</SUB>22 model best fits the neutron diffraction data, and allows structure refinement using rigid carbonate groups. Research was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U. S. Department of Energy.