The Iskoort are a race of aliens from the Animorphs series by K.A. Applegate. They are made up of two parts - an "Isk" and a "Yoort." The Isk is the main physical body, and the Yoort is a slug which must leave the Isk every three days to soak up kandrona rays. The difference between the Yeerk and the Yoort is that the Yeerk are parasitic, whereas the Yoort and the Isk are symbiotic - one cannot live without the other. The Yoort were originally parasitic, but felt limited by their choices, so they created the Isk to be their host bodies. Each Iskoort has a designated function in their society - warmaker Iskoort, trader Iskoort, shopper Iskoort, and manufacturing Iskoort are a few examples.