Habitat: Reef, mangrove and seagrass environments. Distribution: Caribbean wide, Florida, and apparently on the Indopacific. Natural History Notes: This sponge has been studied for its biochemical properties but little is reported about its ecology. Depth: 15 - 60 ft. Characteristics: Shape: Arborescent shape, branches 0.5-2.0cm in diameter. Color: Mottled purple/brown to olive green Consistency: firm, slightly compressible Surface: fine conulose surface (1mm between conules) which feels spiny/crunchy due to spicules erupting from surface. Apertures: Simple oscules with raised thin membrane, 0.5-1cm diameter. Oscules not visible in stressed specimen. Skeleton: Spicules are styles (250umx3um), styles (170umx13um), strongyles(200umx10um), and birotulata (14um length). Birotula rare in this specimen. Spicules alighned in very dense bundles (170um diameter). Spicules not specifically arranged in bundles, but mostly parallel to direction of fiber. Others: Purple exudate when compressed, no noticeable odor Notes: Synonyms: Halichondria birotulata Higgin, 1876 Hircinia atra Whitfield, 1901 Hyrtios musciformis Duchassaing & Michelotti, 1864 Iotrochota imminuta Pulitzer-Finali, 1986