The water-snail is important in the life-cycle of a liver fluke. The liver fluke is a parasitic flatworm that infects the liver of various animals, including humans. The adult fluke releases its eggs in the bile ducts of the host, which are then excreted through feces. The eggs hatch in water, and the larvae infect snails. Inside the snail, the larvae multiply and undergo a series of developmental stages, eventually emerging as infectious forms that can infect other animals, including humans, through the consumption of contaminated water or vegetation. Therefore, the water-snail plays a crucial role in the life-cycle of the liver fluke by serving as an intermediate host for the parasite.