In some Demospongiae&Calcarea,oocytes develop from choanocytes; other derive them from archaeocytes.
Sponges provide nourishment to the zygote until it is released as a ciliated larva (called Parenchymella larva).
In some , when one sponge release sperms, they enter the pores of another. Choanocytes phagocytize the sperm & transfer them to carrier cells that carry sperm through mesophyl to oocytes.