Acantharians are planktonic protists (abundant in today oceans), sister-group to polycystine Radiolarians, that have the particularity of biomineralizing complex skeletons in strontium sulfate SrSO4 (i. e. celestine). Those protists have no (as far as I know) fossil record for the good reason that celestine is soluble in seawater once the organism decayed. However it has been speculated (e. g. Bernstein et al. 1992) that acantharian-derived celestine could be at the origin of the formation of Sr-rich barite.
What is the status of this hypothesis? If this is still considered true, is there a way to differentiate unambiguously acantharian-derived barite from other kind of barite?
This would of course have interesting paleontological implications.
Bernstein, R. E., Byrne, R. H., Betzer, P. R., Greco, A. M., 1992. Morphologies and transformations of celestite in seawater: The role of acantharians in strontium and barium geochemistry. Geochimica et Cosmochimica Acta, 56: 3273-3279.