First person to use this name on MO: Thomas Laxton
Forming both sporocarps and simple or branched plasmodiocarps, gregarious to crowded, sessile, pulvinate, 0.3-0.8 mm diam., up to 5 mm long. Myxocarps with sparse lime nearly black due to the spore-mass showing through the peridium. Peridium grey, somewhat iridescent, roughened with deposits of white lime. Dehiscence irregular. Hypothallus inconspicuous, narrow, transparent, with or without lime. Columella when present, massive, irregular in shape. Capillitium physaroid, tubules hyaline with small, white, rounded or angular lime nodes. Spore-mass black. Spores free, purple brown, smooth or verruculose, oval but appearing globose when viewed from one end, with an apiculus at one or both ends and some having a pale line of dehiscence, 8-10 × 10-14 µm diam. Plasmodium hyaline to yellow, turning milky when beginning to coalesce. Developing myxocarps turning black with grey spots of lime appearing on the surface.
Taken from: http://www.discoverlife.org/...: