The hatchling is called a "miracidium," a free-swimming, ciliated larva. An egg landing in fresh water hatches and releases a ciliated miracidium. Each miracidium is either male or female. The miracidium grows into the sporocyst stage. He gave a comparative description of the egg and miracidium of the fluke. The first snail host is penetrated by a miracidium, producing a sporocyst. The miracidium can be seen inside the fertilised egg. In water, the eggs hatch and release miracidium that in turn infect a snail. During the embryonation of the egg, a larva called a miracidium develops from germinal cells. Inside the snails gut, the miracidium becomes a sporocyst which then begin to produce rediae. Inside the snail, the miracidium sheds its epithelium, and develops into a mother sporocyst. Within the visceral mass of Dreissena, the miracidium transforms into a mother (primary) sporocyst. Fully developed miracidium releases the operculum of the egg using several proteases. The miracidium searches for a suitable freshwater snail belonging to the genus "Biomphalaria". After attaching to a suitable snail host, the miracidium penetrates into the snail body.