Often called "splash cups", the fruiting bodies are adapted for spore dispersal by using the kinetic energy of falling drops of rain.

[2] The "eggs" inside the bird's nests (technically known as peridioles) are hard waxy shells containing spores, and tend to stick to whatever nearby herbage they land on, thus increasing the odds of being consumed and dispersed by herbivorous animals.

The three known Crucibulum species (C. laeve, C. parvulum, and C. cyathiforme) are distinguished from other genera of the Nidulariaceae by their relatively simple funiculus – a cord of hyphae that connects the peridiole (the "eggs") to the exterior of the bird's nest.

For example, the French botanist Jean-Jacques Paulet, in his work Traité des champignons (1790–3), erroneously suggested that peridioles were ejected from the fruiting bodies by some sort of spring mechanism.

[4] The structure and biology of the genus Crucibulum was better known by the mid-19th century, when the brothers Louis René and Charles Tulasne published a monograph on the bird's nest fungi.

[13] Young specimens have a thin layer of tissue called an epiphragm that covers the top of the peridium; it wears off at maturity to expose the peridioles within.

This method of spore dispersal, first suggested by John Ray in the late 17th century, was tested experimentally by Martin (1927),[14] and more thoroughly by Buller and Brodie in the 1940s.

[21] The life cycle of Crucibulum, which contains both haploid and diploid stages, is typical of the species of Basidiomycota that can reproduce both asexually (via vegetative spores), or sexually (with meiosis).

Spores germinate under suitable conditions of moisture and temperature, and grow into branching filaments called hyphae, pushing out like roots into the rotting wood.

When two homokaryotic hyphae of different mating compatibility groups fuse with one another, they form a dikaryotic mycelia in a process called plasmogamy.

Prerequisites for mycelial survival and colonization a substrate (like rotting wood) include suitable humidity and nutrient availability.

Crucibulum laeve is saprobic, so mycelial growth in rotting wood is made possible by the secretion of enzymes that break down complex polysaccharides (such as cellulose and lignin) into simple sugars that can be used as nutrients.

Fruiting body formation is influenced by external factors such as season (which affects temperature and air humidity), nutrients and light.

[24] The initial studies on the development of the fruiting bodies in Crucibulum were performed by the brothers Tulasne (1844),[5] Sachs (1855),[25] DeBary (1866),[26] Eidam (1877),[27] and Walker (1920).

[11] C. parvulum has been found on the roots and stems of old or dead dry land plants such as Juniperus horizontalis and Artemisia species.

It has been collected in most European countries and the Canary Islands; in North America it has been found from Alaska to Mexico, while South American locations include Chile and Tierra del Fuego.

[10] C. parvulum has a primarily North American distribution, having been found in Alaska, southern Alberta Badlands, the Canadian Rocky Mountains and in semi-deserts of Idaho;[37] in 2004 it was collected in China.

[40] Species in the family Nidulariaceae, including Crucibulum, are considered inedible, as they are "not sufficiently large, fleshy, or odorous to be of interest to humans as food".

It differs from Crucibulum laeve in the shape and pink-color of its peridia, as well as its slightly or strongly curved spores (typically 6.5–8 x 11–17 μm).

[43] The immature fruiting body of Crucibulum laeve (technically, the peridium), is roughly spherical in shape, but in maturity the base is narrowed slightly relative to the top, so that it appears like a cup, or crucible.

Young species have a yellowish velvety cover of fine hairs, but this external surface becomes sloughed off and becomes smooth as the fruiting body matures; the color changes to brown, although some old weathered specimens may be bleached grey or dirty white.