During the polygastric phase, Rosacea plicata exhibits a pair of large, smooth, round to oval nectophores of equal size. Once the larval nectophores are shed, new nectophores develop from reserve bells. The somatocyst is slender and thread-like, positioned near the dorsal wall of the hydroecium. It bends at the apex of the hydroecium and extends downward beyond the pedicular canal. There are no tubercles, pigment spots, or tentacles around the mouth of the nectosac. The gonophores bear male or female germ cells on a short manubrium. The radial canals are simple, straight, and connect with the circular canal.