Parasite; derived from the Latinisation of the Greek word parasitos, "one who eats at the table of another" 

Leucochloridium Paradoxum is a parasitic flatworm found throughout Europe and North America. It houses itself inside the bodies of small land snails, ingested via bird faeces which the snails feed on. Spending its early days inside the digestive system of the snail, the worm eventually grows into what appears to look like a large caterpillar or grub. The worm then invades the antenna of the snail, causing them to swell and pulsate. This causes a deficit in light detection, encouraging the snails now in a zombie like state, to wander out from under the cover of leaves and trees. This makes them open targets for birds who regular diet is made up largely of caterpillars and grubs. The Flatworm now has a new host in which it can reproduce, laying its eggs in the stomach of the bird.  These eggs are then dispersed back into the world through its excrement to be eaten by snails.