Encrusting Rose Sponge

Growth form encrusting, thin (3–6 mm), in irregular patches of up to 20 cm in diameter. Surface evidently conulose (1–3 mm) because of the dense dendritic “forest” of “small horny trees” forming the typical skeleton of all Aplysilla species. Oscules (1–3 mm) scattered and not evident; inhalant apertures rarely visible in vivo. Colour from rose to yellow. Skeleton of large ramified fibres arising from a spongin basal plate strictly adhering to the substratum. Dendritic fibres with maximum size of ca. 5 mm in length, ca. 300 µm in diameter at the basal portion, and no more than 50 µm in diameter at terminal branches (up to 4–6 sometimes anastomosing). Spongin layered, transparent, pale in colour, not cored with mineral debris.