Neither plants, nor animals, nor fungi, the myxomycetes are a surprisingly diverse and fascinating group of organisms. They spend the majority of their life out of sight as single-celled amoeboid individuals in leaf litter, soil or decaying wood, foraging for bacteria and other simple life forms. However, when conditions are right, two individual cells come together to give rise to a much larger, creeping structure called a plasmodium, which produces even more complex and often beautiful fruiting bodies. Indeed, the fruiting bodies of myxomycetes are often miniature works of art! Their small size (usually only a few millimetres tall) and fleeting fruiting phase mean that these organisms, although ubiquitous and sometimes abundant, are overlooked by most people. However, recent research by a few dedicated individuals has shown that Australia has a very diverse myxomycete biota with more than 330 species, the largest number known for any region of the Southern Hemisphere. This comprehensive monograph provides keys, descriptions and information on the known distribution for all of these species in addition to containing introductory material relating to their biology and ecology. Many species are illustrated, showing the diversity of their fruiting bodies, and greatly facilitating their identification.