Fungi, which used to be considered part of the plant kingdom, are now placed in their own kingdom. Slime molds, which used to be considered fungi, are now part of the Protista kingdom. Lichens are composite, symbiotic organisms, made up of as many as three partners. The dominant partner is a fungus, and the second partner is either an alga or a cyanobacteria, and in a few cases, both. Because the fungus cannot produce its own food, it relies on its algal or cyanobacteria partner for photosynthesis.