"The lancet fluke (Dicrocoelium) infects the brain of ants by taking control and driving them to climb to the top of a blade of grass where they can be eaten by a cow. The ingested fluke then lays eggs in the cow gut. Eventually, the eggs exit the cow, and hungry snails eat the dung (and fluke eggs). The fluke enters the snail's digestive gland and gets excreted in sticky slime full of a seething mass of flukes to be drunk by ants as a source of moisture."