This last group of protozoans is non-motile, and parasitic. Non-motile refers to the fact that these protists do not have cilia or flagella to help them move from place to place. Instead, they "move" by means of using hosts. They have very complex life cycles, involving intermediate hosts such as the mosquito. They will begin their life cycle in the mosquito host, and then when that infected mosquito bites a human, the parasitic protist is transferred to the human. They form small resistant spores, small infective bodies that are passed from one host to the next. To help them do this, the Plasmodium has a cellular structure known as the apical complex. This is what the Plasmodium uses to attach itself and penetrate into the host's body.