Radiospongilla crateriformis typically forms thin and small cushions with a more or less even surface. The sponge can appear flesh-colored to light green. Although the oscula are numerous, they are not conspicuous. The dermal membrane is well-developed, and the skeleton is composed of irregular spicule fibers cemented together with a small amount of spongin. The live sponge has a soft consistency. The megascleres are slender, fusiform, and sharply pointed at both ends, known as amphioxea. The terminal ends bear sharp microspines. Their dimensions range from 240-300 µm in length and 9-11 µm in width. True microscleres are absent. Gemmoscleres in Radiospongilla crateriformis are typically slender, amphistrongyla (blunt or rounded at both ends), slightly curved, and covered with variable numbers of minute, conical spines. Additionally, they have one or several rows of radiating weakly recurved spines terminally. The length and width of gemmoscleres range from 60-75 µm and 3-5 µm, respectively. Gemmules are rounded and fairly numerous. The pneumatic coat is thick, well-developed, and composed of minute irregular air spaces in which gemmoscleres are embedded radially but frequently cutting across one another at different angles. The foraminal tube is short, straight, and porous. Gemmoscleres surrounding this tube are rather slant and form crater-like depressions around the micropyles. The diameter of the gemmules ranges from 370-450 µm.