An egg of Fasciola hepatica or the common liver fluke. Scanning electron micrograph (SEM). The eggs of the liver fluke are secreted into the bile duct of the host animal, where they pass through the gut to be excreted into the outside environment, if there is water presents the eggs will hatch into midacidium larvae, which are infective to the intermediate host a Mud Snail, Galba truncatula. Magnification: x3000 at 10 centimetres wide.