From a distance looks like a streak of ashes deposited on grass, or on live or dead plant stems and leaves. Close up it appears as many miniscule ash-colored balls, some of which break open to reveal a darker gray inside. Appears in late summer or fall.
Most of this organism's life is spent as a bit of slime crawling through the dirt devouring microscopic organisms, but when conditions deteriorate or food runs out, it crawls upward onto grass or other vegetation and differentiates into the sheet of ashy balls. This is the reproductive form, and when the balls break open, spores are released to start new individuals.
When conditions are favorable, may be found on grass or dead or living vegetation in reasonably moist places. This species is sometimes listed as a pathogen of turfgrasses, but it uses the grass only to climb up and disperse its spores, thus causing little or no harm to the grass. Lawn owners and golf course managers, however, often suffer psychological harm on discovering it, so perhaps it should be considered a pathogen of turfgrass owners.
The tiny ashy balls are reasonably distinctive and make identification fairly easy.