The seahm is categorized into the Division of Headbells, a transparent, tapered marine animal, ranging in length from 3.5 to 5 cm. The embryos are fertilized and fertilized in this animal externally. After an hour of fertilization, the stages of spawn, which are of the complete and equal type, begin to divide until the stage of the formation of the plastula, which is characterized as a hollow-like structure consisting of one layer of cells. Which represents an initial differentiation stage where the three bacterial layers are formed and the organismic phase begins.
