Cyathus stercoreus (Bird's nest fungus)

This is a Birds nest fungus The fruit body is somewhat like an upside-down cone, for it tapers towards the base. When immature the mouth of the cone is covered by a membrane (the epiphragm). At maturity the epiphragm breaks to leave the mouth open and reveal the ‘eggs’ (or peridioles) within the cone. Spores are produced within the peridioles. The mature fruit body may be 5 to 15 millimetres tall and 4 to 8 millimetres wide. The outer surface is initially very shaggy and often golden brown or similar but a range of shades of brown are found. Old, weathered specimens may be bleached and much smoother. When mature, the inner wall is smooth and lead-coloured.

The peridioles are black and often are attached to the inner wall of the fruit body by a cord (the funiculus). It is common to see it said that the peridioles of this species have funiculi – however that is certainly not always so (for an example see https://canberra.naturemapr.org/Community/Sightings/Details/4201813). Some studies note that funiculi may be absent from the upper peridioles in a fruit body and H.J. Brodie (page 168 of The Bird’s Nest Fungi, University of Toronto Press, 1975) says that in some collections “no funiculi can be seen, a situation which has frequently resulted in this species being identified as a Nidula”.

This cosmopolitan species appears on herbivore dung, soil (in particular on rich soils), woodchips, composted materials or other organic debris.

This is probably the commonest Birds nest fungus in the Canberra area and I have seen it in many suburban gardens or nature strips. It may appear in large colonies. I once saw a dense colony (within a 15 x 15 cm square) outside the National Library and stopped counting at 200.

Look-alikes

 If you see a very shaggy Birds nest fungus, with a smooth, lead-coloured inner wall and black peridioles you probably have Cyathus stercoreus. However, as I noted above, there is variation in colour and there is weathering to consider so sometimes it could resemble other species of Cyathus. Then a microscope is necessary and Cyathus stercoreus is blessed with what, for a Birds nest fungus, are unusually large spores. They are thick-walled, broadly-ellipsoid to globular and usually range from 20 to 40 mm  in diameter (even within the one peridiole).

Though the fruit body broadens towards the mouth, it does not flare out as does Cyathus olla (https://canberra.naturemapr.org/species/3779)

An epiphragm is present in Nidula, but in that genus the peridioles are greyish, light brown to reddish brown.

There is an identification key to genera at https://canberra.naturemapr.org/categories/guide/1736.