Tectitethya crypta (de Laubenfels, 1949) Hadromerida, Tethyidae Common Names: None. Growth Form: Massive; amorphous to irregularly hemispherical. Surface: Usually entirely sediment-covered with only oscules visible; often overgrown with fleshy and filamentous algae. The sponge surface under the sediment is irregularly covered by small flattened tubercles 2-3 mm across. Color: Usually white or light grey due to sediment cover. Blackish green when cleaned. Consistency: Firm, tough, slightly compressible. Exudate: None. Oscules: Single, central, dark-rimmed, irregular and rounded; variable in size, often 2 cm or more across. Several may be evenly distributed in large specimens. Skeletal Components (Spicules, Fibers): Rods thickest in the middle and tapering toward both ends, with one end rounded and the other end pointed (strongyloxea), 500-1400 x 10-40 μm. Two kinds of microscleres: small stars with 8 regular blunt-tipped rays (strongylaster), 8-12 μm across; larger stars with irregular rays, often with forked tips (megaster), 10-40 μm across. Skeletal Architecture: Exterior: Endings of strong bundles of spicules push up the surface as flattened tubercles, with an outer cover of small star spicules. Interior: Large spicules make thick bundles of up to 1 mm diameter, which radiate and subdivide into thinner bundles. Larger star spicules form a layer beneath the exterior skeleton. Sediment particles occur everywhere among the bundles. No visible spongin. Ecology: In lagoonal environments on sediment-covered bottoms. Distribution: South Florida and Caribbean-wide (Florida, Bahamas, Dominican Republic, Jamaica, Belize). Notes: Very few species are so densely covered in sediment as Tectitethya crypta; in combination with the dark-rimmed oscules, this is diagnostic. Tectitethya keyensis is very similar but is more definitely lobate and conical, with a less dense sediment cover that reveals more of the sponge’s brown (rather than blackish-green) surface. Its large star spicules are larger than those of T. crypta, with regular rather than irregular rays. Spheciospongia vesparium occurs in the same habitat, and smaller, low-growing specimens may look similar, but it is more definitely black with clustered oscules. Spongia species may be similar in shape but are not so covered in sediment. Stelletta kallitetilla may look similar when covered with sediment, but is yellow-brown, fist-shaped, and more upright, with many flush oscules scattered over the entire surface. Reference(s): de Laubenfels (1949, as Cryptotethya), Wiedenmayer (1977, as Tethya), Sarà & Bavestrello (1996). Similar species: Tectitethya keyensis Spongia pertusa Spongia obscura Geodia gibberosa Spheciospongia vesparium Aaptos pernucleata