Radiospongilla cinerea typically forms small, flat encrustations, and the live sponge has a relatively brittle or fragile consistency. The coloration varies from ash-grey to bright green, attributed to the presence of unicellular algae, Chlorellae, residing in their tissues. The megascleres in Radiospongilla cinerea are fusiform, weakly curved, and sharply pointed. They are covered with minute and indiscernible spines, except at the terminus. The dimensions of these spicules range from 230-310 µm in length and 8-10 µm in width. True microscleres are absent. Gemmoscleres in this species are more or less abruptly pointed at both ends, slightly curved, and completely covered with rather coarse spines. These spines are grouped terminally without a significant increase in length. The length and width of gemmoscleres range from 47-62 µm and 3-4 µm, respectively. Gemmules are rounded, and the pneumatic coat is well-developed. It consists of clearly distinguishable subspherical air spaces or appears granular without apparent air spaces. Gemmoscleres are embedded strictly radially in a single layer within the pneumatic coat. The foramen tube is straight, slender, and porous. Gemmules have a diameter ranging from 310-330 µm.