Calcaronea

Calcaronea is a subclass in the class Calcarea.They are Calcarea with the triactines and the basal system of tetractines sagittal (i.e. the rays of the spicule make unequal angles with each other), exceptionally regular. In ontogeny the first spicules to be secreted are diactines. Choanocytes are apinucleate. Calcaronea have amphiblastula larvae