the stages started as an egg, layed by the female, the eggs that are layed, comes out of thier mouth, inside, the plankton dies and decomposed by bacteria, later, the cells are there, creating a eggs. another thing that creates eggs are the dead orginisms, as it is, the dead orginism like dead humans, who are in the ocean decomposed, but the cells are left for the female to make eggs, the dead cells will turn into eggs inside. Notice that it would get a female if it were made by the dead orginisms cells and bacteria trapped, the male is made by the zooplankton cells, and the protozoa.