Amphiblastula

Peculiar blastula which is formed in the development of calcareous sponges. The segmentation of the sponge ovum results in a spheroidal ma of cells, that are large and granular at one end of this blastula, and are small and flagellated at its opposite pole. The next stage is the pseudo gastrula , followed by a return to the amphiblastula condition, and then finally by the development of the para gastrula .