Parasites are organisms that live inside or on another species, called the host. Parasites depend on their hosts for food and a place to live. They may harm the host in small or large ways. Parasitism is the most common mode of life on Earth. Humans, other animals, and all plants have parasites, usually two or more kinds. Even parasites can have parasites. There are millions of species of parasites, and scientists discover new ones every day. Parasite specimens are stored in museums all around the world. One of the world's largest collections is in the H. W. Manter Laboratory of Parasitology at the University of Nebraska State Museum.