I’m not sure of this one – it looks like an old earth star (Geastrum species), but I can’t see any ‘rays’. Perhaps they have rotted away. It’s on the sand dunes at Flat Rock. The globe contains the tiny spores, which puff out of the central hole.
I’m reassured by a photo (on p. 116 of Shepherd and Totterdell’s Mushrooms and Toadstools of Australia) of Geastrum triplex which also has the globe and base but no ‘rays’.
Here’s what they normally look like – these are at Barkers Vale, just north of me.
In some species the globe is pushed high by the ‘petals’ so the spores can puff out further away from the globe. ‘Earth star’ is such a magical name.