The below mentioned article provides a diagram of amphiblastula (larva).
1. It is a free swimming larval stage of Sycon and many other calcareous sponges.
2. The body is some what ovoid in form and is comprised of an anterior half of small flagellated micromere cells and a posterior half of large non-flagellated macromere cells.
3. It encloses a small cavity the inside of which is filled with amoebocytes.
4. It develops from stomoblastula through a process of inversion.
5. It leads a free swimming existence for some times and then settles down at bottom and gives rise to young sponge through embolic gastrulation.
6. The micromeres give rise to choanocytes lining radial canals and macromeres give rise to the rest of the layers.