I think the ants tending the white globes is the clue here. Badhamia is a slime mould genus which doesn't look quite right in the context presented here. The white things look like one of the scale insects (perhaps a species of Eriococcus?) and the ants are coming to their secretions.
That may very well be right - I came across Badhamia as a tentative identification ages ago and recall that the ants seemed to make sense then but I now can't find anything suggesting ants would like it.
Further to Ken's comment, on page 135 of Roger Farrow's 'Insects of south-eastern Australia' I found a photo of ants attending Cryptes baccatu, a scale that looks like the subject of this sighting and then found several sightings of this scale species on Canberra Nature Map.