Spongia tubulifera Lamarck, 1814 Dictyoceratida, Spongiidae Common names: Cuban Reef Sponge. Growth Form: Massive, sometimes sprawling, with upright oscule-bearing lobes, up to 30 cm wide, 15 cm high; smaller specimens are common. Surface: Smooth, slippery, finely conulose, especially on the sides; no visible pores; some sediment may be present on the upper surface. Color: Black or very dark grey externally; tan or orange-brown in the interior; paler on the sides near the substrate. Consistency: Compressible, elastic. Exudate: None. Oscules: Round, thick-walled, irregularly distributed, at the top of upright lobes, about 0.5-2 cm across, and often taking up the entire width of the lobe, no collar membrane. Skeletal Components (Spicules, Fibers): Spongin fibers only; no proper spicules. Spongin orange, not laminated. Most fibers are simple, up to 50 μm across. Slightly thicker fibers (100 μm across) cored by sand grains and broken foreign spicules arise at intervals of up to 2 mm. Skeletal Architecture: Fibers make an irregular meshwork; meshes of variable size and shape, 50-700 μm in diameter. Ecology: Common in lagoons and shallow bays. Distribution: South Florida, Gulf of Mexico and throughout the Caribbean. Notes: Difficult to distinguish from other local Spongia species, although the shape of the oscular lobes is diagnostic. Two other local species are also black. Spongia pertusa has a similar habit, but the oscular lobes are lower and mostly mound-like, and the fibers and meshes slightly finer. Spongia obscura tends to be inverted conical with oscules concentrated at the flattened top. Three other species: cup-shaped S. tampa, globular S. barbara, and deeply grooved S. graminea, have not been verified in South Florida waters for decades. All Spongia species are much more compressible (“spongy”) than other local massive black or dark species, such as Spheciospongia vesparium, Ircinia strobilina, Aaptos pernucleata, Tectitethya keyensis and Geodia gibberosa. Reference(s): Wiedenmayer (1977), van Soest (1978). Similar species: Spongia pertusa Spongia obscura Spheciospongia vesparium Geodia gibberosa Aaptos pernucleata Ircinia strobilina Tectitethya keyensis