Ascomata apothecial, scattered or usually thickly gregarious, at first slightly sunken and closed, globose or hysteriform, at maturity expanded, superficial, sessile, typically patelliform or occasionally elliptical, with an elevated margin, reaching a diameter of 225-690 mm; black, smooth, carbonaceous when dry, subgelatinous when moist, disc smooth, plane or slightly convex; excipulum 20-40 mm thick, composed of close parallel septate hyphae, the inner periclinal hyphae thick walled and hyaline, the outermost rows with thick brown-black walls; Hypothecium 50-80 mm wide, the cells just below the hymenium with thin hyaline walls, those of the basal part elongated and with dark thickened walls.

Asci 8-spored, clavate, short stipitate, rounded above with the wall thickened at the apex, reaching a length of from 74-145 mm and a diameter of 16-24 mm;

Ascospores irregularly biseriate, clavate, with the apex blunt and gradually tapering below, often slightly curved, hyaline, 5-11 septate (mostly 7 septate), the cells usually containing 1 or more oil drops, 27-39 mm long by 7-10 mm wide.