Brown tube sponge
The sponge grows in semi-incrusting thick branches or lobate masses, from which mound-shaped, hemispherical, cylindrical or conical protuberances with conspicuous apical orifices commonly arise. These may be a few millimeters to 50 cm high above the basal mass and 2.5-25 cm in diameter (A. conifera habitus). The surface is finely rugose to verrucose. There are three sorts of oscules: 1) circular, apical oscules, 5 mm to over 5 cm in diameter, with a strong, somewhat recessed, sphinctrate diaphragm; 2) elongate, contorted invaginations, between the elevations or on the sides of higher protuberances, 2-3 mm wide and up to 3 cm long; 3) small, circular crowded vents, about 1 mm wide and 1-3 mm apart, scattered over wide areas, contractile and inconspicuous. The consistency is stiffly spongy.
Light purplish brown and somewhat mottled on the surface; yellow in the atria, around the base and in the interior.
Inhabit reefs and walls, especially in sheltered environments. Golden zoanthids (Parazoanthus swiftii ) and Maroon sponge zoanthids (Parazoanthus puertoricense ) may grow on the surface.
Occasional Florida; common Bahamas and Caribbean.