Peziza atrovinosa Cke. & Gerard Cup 2-5cm across, quite deeply cup-shaped, sometimes becoming contorted in age or from pressure of overlapping cups; inner surface brown becoming almost black with an olivaceous tinge from a dusting of spores, outer surface cinnamon brown to smoky. No stem. Asci 275 x 14µ. Spores ellipsoid, smooth, containing 1 or 2 oil drops. 10 x 15-17µ. Habitat in groups or sometimes dense clusters on the ground or among moss in woods. Rather common. Found in eastern North America arid Montana. Season June-September. Not edible.