Most likely Astraeus hygrometricus. Did you happen to feel the star-like arms? In that species they are quite tough (even feeling woody when dry) unlike the fleshy arms in the earthstars of the genus Geastrum.
Another thing I should have asked is: Are there any non-Australian trees nearby? The species is reported as forming symbiotic associations with various trees of the northern hemisphere.
Thank you. I actually thought they were lizard eggs, until I saw the photos and realised they were fungi! Yes, there were non-native trees a number of metres away.