Hexadella racovitzai Topsent 1896

Growth form encrusting, thin, with lobes in large patches. Colour faded to pale pink in vivo, brownish in ethanol after releasing of a yellow fluid. Surface highly wrinkled by small evident collagenous reinforcements irregularly crossing and converging towards small conules; well developed (when compared to Hexadella pruvoti and Hexadella crypta) star-shaped network of subdermal canals converging towards oscula; inhalant apertures inconspicuous. Oscules wide, at the apices of short chimneys. Ectosome notably thick. Choanosome soft, fleshy and fragile, difficult to cut. Large clusters of spherulous cells, common at the body surface, with large inclusions containing microgranules and microgranular cells; choanocyte chambers eurypylous (30±6.3 × 19±2 µm on average) in dense clusters. High natural toxicity.