Slime moulds are now classified as a separate kingdom from fungi, sharing some of the characteristics of amoeba and fungi.
A Field Guide to the Fungi of Australia explains:
Slime moulds have unusual life cycles in that they produce a fruiting body and spores, but in many instances, a germinating spore produces a cell that is able to move about actively and ingest food rather like an amoeba. This cell feeds and reproduces by simple fission until there are perhaps thousands of daughter cells. A chemical signal then causes the cells to combine and form the fruiting structure or structures for that particular species.
Like many slime moulds, the cells of this species [Fuligo septica] typically aggregate to form a plasmodium, a multinucleate mass of undifferentiated cells without cell walls that may move in an ameboid-like fashion engulfing particles of food such as bacteria, spores of fungi and plants or protozoa. Fuligo septica plasmodium may be anywhere from white to yellow-gray, typically 25–200 mm in diameter, and 10–30 mm thick.
The plasmodium eventually transforms into a sponge-like aethalium, analogous to the spore-bearing fruiting body of a mushroom; which then degrades, forms a crusty white surface, under which are dark-colored spores.
These tiny (2-3mm long) fruiting bodies were observed on decaying wood and leaves in early May. The top two images show the early stage of the fruiting bodies after which iridescent blue to black spores appear on the surface on white stalks.
Fuligo septica – Flowers of Tan
Plasmodia are usually hidden, moving around mostly at night, but it may be that the white and yellow masses seen close up on the surface of these aethalium are fragments of plasmodia. This species is known to have its spores dispersed by beetles of the Latridiidae family which feed on moulds and larger fungi. Fuligo septica produces millions of spores and the largest spore-producing structure of any known slime mould.
Fuligo septica occurs in many countries and can be found in the Park close to the path under the mature trees opposite the BBQ area and a particularly large example (~500mm long x 200 wide) was seen close to the edge of Horseshoe Lake in April 2012. It has not been observed in 2013.
The plasmodium of Leocarpus fragilis is at first lemon then orange-yellow and the sporangia, 2-4mm long, are stalked and often densely clustered, turning from shiny yellow or orange to brown before opening to release dark purplish-brown spores.