The number of nectophores within a Hippopodius hippopus colony can vary, ranging from just a few to several pairs. The larval nectophore is caducous, meaning it is shed and then replaced by a sequence of secondary heteromorphs that persist throughout the organism’s life. In younger nectophores, the rete mirabele found in the ventral radial canal is substantial, appearing large, opaque, and taking on a rounded, bilobed, or pear-shaped shape. However, in older nectophores, it is notably reduced, becoming thin and cigar-shaped or even absent.The somatocysts are elongated and slender, resembling thread-like structures. The hydroecium is deep and dome-shaped, accommodating a younger nectophore. Both male and female gonophores are found together in clusters at the base of the gastrozooids within each cormidium.