I suspect this is a slime mould but would need a much closer view of the structures to hazard a guess as to which one. A useful website on the group is https://www.discoverlife.org/mp/20q?search=Eumycetozoa&guide=Myxomycetes&flags=HAS:
Heino Lepp has advise me that it's very likely Leocarpus fragilis (a slime mould) that is fairly common in Canberra, and that it's part way to the mature sporing stage.
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