Slime moulds are a diverse group of organsims that are neither plants, animals nor fungi. They spend most of their life as microscopic single-celled amoeboid individuals in leaf litter, soil or decaying wood, and when conditions are right they reproduce and form a larger, spreading structure called a plasmodium, which in turn produces fruiting bodies (Secretive Slime Moulds: Myxomycetes of Australia By Steven L. Stephenson).
For beginners, here is a “A Key to Common Genera of Slime Moulds” written and illustrated by Peta McDonald, a Melbourne primary school teacher: https://upload.wikimedia.org/wikipedia/commons/f/f6/A_Key_to_Common_Genera_of_Slime_Moulds.pdf
A more technical key can be found in “Taxonomic Keys and Plates from The Myxomycetes”, a book by George W. Martin and Constantine J. Alexopoulos: https://www.myxotropic.org/wp-content/uploads/2021/04/MyxoKeys.pdf
For a photo gallery of slime moulds from around the world check out this one on a Spanish myxomycetes website: https://www.myxotropic.org/galeria/
Further information:
Physarum sp. (genus) at Kianga, NSW
Lycogala epidendrum (Complex) at Kianga, NSW
Fuligo septica at Pilot Wilderness, NSW
Fuligo septica at Pilot Wilderness, NSW
Ceratiomyxa fruticulosa at Kianga, NSW
Fuligo septica at Murrumbateman, NSW