In the Zygomycota, and especially in the Mucorales, the asexual spores are contained in globose sporangia or cylindrical merosporangia. Because they are non-motile, the spores are sometimes termed aplanospores (Gr. a = not, planos = roaming).
The sporangiospores may be uni- or multinucleate and are unicellular. They generally have thin, smooth walls and are almost always globose or ellipsoid in shape. They are formed by cleavage of the sporangial cytoplasm. They vary in color from hyaline (colorless) to yellow, due to carotenoid pigments in the cytoplasm.
When mature, they may be surrounded by mucilage, in which case they are usually dispersed by rain splash or insects, or they may be dry and dispersed by wind currents.
In some genera, e.g. Pilobolus, entire sporangia become detached. The number of sporangiospores per sporangium may vary from several thousand to only one. The detachment and dispersal of intact sporangia containing a few sporangiospores or a single one are indicative of the way in which conidia may have evolved from one-spored sporangia.