Cyathus sp. (A Bird's Nest Fungus)

The fruit body is an urn- or vase-shaped structure in which, at least initially, there are a number of small ‘eggs’ (or peridioles). The fruit body may be up to 15 or so millimetres in height and 10 wide at the top (but often less), usually narrowing towards the base. The outer surface may be creamy, greyish or some shade of brown and often is hairy. When immature a membrane (or epiphragm) covers the top of the ‘urn’. The disc-like peridioles are 1-3 millimetres in diameter, dark brown to black and each is attached to the ‘urn’ by a fine cord.

The fruit bodies appear on soil, well-rotted wood, herbivore dung or doormats in a wide variety of habitats and usually in groups, often quite large.

Look-alikes

Crucibulum – The peridioles are whitish,  pale grey or yellowish and have attachment cords. An epiphragm is present in immature fruit bodies. Fruit bodies are squatter, with height closer to breadth, and hence more cup like, whereas those of Cyathus are generally noticeably longer than wide. I have seen fresh Crucibulum fruit bodies grow inside old ‘cups’, so that the wall of an old fruit body surrounds the new fruit body. I have not seen that in the other genera.

Nidula – The peridioles are greyish, light brown to reddish brown, lack connecting cords and are embedded in gelatinous material (absent in both Crucibulum and Cyathus). Immature fruit bodies have an epiphragm.

Nidularia -  The fruit body is roughly globose, up to 10 millimetres in diameter and breaks irregularly to expose the brown peridioles (which had been embedded in gelatinous material and had no attaching cords). Hence, in this genus there is neither ‘urn’ nor ‘cup.

A few other genera have fruit bodies no more than 3 millimetres in diameter.

There is a key to the genera of Birds nest fungi at https://canberra.naturemapr.org/Community/Categories/Guide/1736.