Sturgeon and paddlefish (Acipenseridae) sagittal otoliths are composed of the calcium carbonate polymorphs vaterite and calcite.

This study sought to resolve whether sturgeon (Acipenseridae) sagittae (otoliths) contain a non-vaterite fraction and to quantify how large a non-vaterite fraction is using neutron diffraction analysis. This study found that all otoliths examined had a calcite fraction that ranged from 18 +/- 6 to 36 +/- 3% by mass. This calcite fraction is most probably due to biological variation during otolith formation rather than an artefact of polymorph transformation during preparation.