Calostoma fuscum is a stalked puffball from family Sclerodermataceae. It's common name is Common Prettymouth. This unusual and ornamental puffball is found on the ground amongst leaf litter in moist forests, or sometimes emerging from steep earthen banks.
I have encountered these fungi occupying the exact spot by the Williams River in Barrington Tops World Heritage rainforest over several years. They are long lasting, but once any orange colouration darkens to blackish-brown, they are well camouflaged on the forest floor.
The stalk, which I have observed growing to a height of about 80mm, is composed of tough, gelatinous, interwoven strands which can be orange, aging to brown or black. The 15 to 20mm wide stalk is topped with a round head covered with a warty semi-circular cap, or lid, which falls off as the fungus matures.
An orange star-shaped mouth (or stoma) covers a hole in the apex of the head, allowing the white spores to be released when gentle pressure is applied by passing animals or moving vegetation. In the image below, you can see that there are indentations in the head of the fungus below the stoma providing exits for the spores to be dispersed in several directions.
In the picture below, you can see that the star-shaped mouth sits raised to allow escape routes for the spores. The discarded cap has a smooth interior with an imprint of the mouth. The cap falls off in one piece.
I am unsure of the distribution of Calostoma fuscum, but the Fungi Map project of the Royal Botanic Gardens Melbourne shows it to have been recorded in eastern NSW, Victoria, Tasmania, and the Adelaide district of SA.
Calostoma fuscum on a steep earthen embankment
My sightings of Calostoma fuscum
[This will be updated with new sightings]
Barrington Tops NP NSW - On the rainforest floor in soil, flanking the Williams River - Feb, Mar, Apr, May, Jul, Sep, Nov.
New England NP NSW - On steep, damp clay bank - May.
A cluster of Calostoma fuscum, caps discarded