Spongionella gracilis (Vosmaer 1883)

Tubular habit with ten to fifteen slightly clavate hollow cylinders (up to 2 cm high, with a diameter of 5–8 mm) partly coalescing and arising from a common basal spongin plate (ca. 4.5 × 3 cm in diameter). Consistency soft and elastic, as the rule in all Spongionella species. Oscules apical (2–3 mm in diameter). Surface finely conulose with conules supported by tips of ascending fibres (conules ca. 100 µm high, 300 µm apart). Skeleton reticulate with a more or less regular network of generally quadrangular meshes (100–300 µm in diameter). Primary fibres (25–30 µm in diameter) connected by rare and irregular tracts (5–10 µm in diameter). Fibres laminated, clear, and uncored, with a transparent axis.