While playing the game, you will see a shell at the bottom of the tank. Keep tapping the shell until it starts to eat your newborn Seaman. After they are eaten, tap the shell more until the squid completely comes out. It will squirm, and eventually after tapping it enough, it will die and the baby Seaman will appear and will be in the next stage (Gillman). Hold A while talking into the microphone to speak to your Seaman.