As you can see, each capsule contains numerous embryos. The embryos undergo spiral cleavage and develop into trochophore larvae at around the forth day after egg deposition.
M. Wolf. 2012. The reproductive ecology of a northeastern Pacific nudibranch, Janolus fuscus, with an examination of its endoparasitic copepod, Ismaila belciki, Biol. Bull. 222: 137–149.