Cyathus olla also known as the field bird's nest is a species of saprobic fungus in the genus Cyathus of the family Nidulariaceae. The fruit bodies resemble tiny bird's nests filled with "eggs" – spore-containing structures called peridioles. Like other bird's nest fungi, C. olla relies on the force of falling water to dislodge peridioles from fruiting bodies to eject and disperse their spores. The life cycle of this fungus allows it to reproduce both sexually, with meiosis, and asexually via spores. It is a relatively common fungus, with a worldwide distribution.