Spongionella pulchella (Sowerby 1804)

Growth form of Mediterranean specimens cushion-like, small (2 cm in diameter, 5–10 mm in thickness). Colour grey-greenish-brown. Consistency soft and elastic. Surface finely conulose with conules supported by tips of ascending fibres. Inhalant apertures not visible, oscules small (0.5–1 mm) and rare. Flagellate chambers large (70–80 µm) with small choanocytes. Skeleton network typical of the genus, extremely regular and practically indistinguishable from that of Spongionella gracilis. Fibres laminate, light and transparent, with axial pith lacking of inclusions that, when evident, shows a typical aplysillid structure. After Topsent (1929): primary fibres of a single dimensional class (25–35 µm); rare and irregular secondary connecting tracts (7–25 µm); meshes generally quadrangular 120–300 µm in diameter.