It is a phylum of palastic animals. It lives an parastices on beetles, cockroaches, crustaceans etc and it eats organs of the hosts. But the hosts can still survive continually. Adult Nematomorpha are free living, But Before free livng it has to go to some watery places. So it controls the host's brain, gives a thought or something to the brain of host 'go to the water' and makes the host jump in the water. And then it comes out. But the host doesn't know, what is he(the host) doing and dies.