Several specimens of the large, discoidal, new inozoid genus and species, Gigantospongia discoforma, have been discovered in the Upper Permian, Upper Capitan Limestone in the northern Guadalupe Mountains of New Mexico, near Carlsbad Caverns. The holotype is nearly 2.5 meters across, as exposed, and ranges from 8-20 mm thick, with numerous canals transverse and parallel to the principal plane. These canals are approximately 1 mm in diameter and separated by tracts 1-2 mm thick. Thickened dermal and gastral layers, each approximately 1 mm thick, occur at tops and bases of both the holotype and associated paratypes in the “Sponge Window” exposures of Bat Cave Draw, and in specimens from Chinaberry and Hackberry Draws. Inverted Lemonea conica Senowbari-Daryan, 1990, is apparently attached to the base, and appears to have grown inverted in a void formed or capped by the tabular inozoid. Well-preserved specimens of Amblysiphonella also appear inverted, as do examples of Lemonea cylindrica (Girty, 1908), a new species of Lemonea, and Guadalupia explanata (King, 1943), which occur between the holotype and an underlying paratype. All appear coated with Archaeolithoporella crusts. Microstructure of the inozoan skeleton is obscured by diagenesis.