The pneumatophore of Agalma haeckeli takes on an ovate or pyriform shape, featuring purple pigment on the upper half and yellow pigment on the lower half. It is marked by eight equidistant longitudinal lines that divide the pericystic cavity into eight radial pouches. The nectosome contains four pairs of nectophores, with the nectosac situated on the lower half of the nectophore. The ostium is adorned with three scarlet-colored pigment spots. Gonodendra are positioned at the bases of palpons, and the gonophores are well-developed, featuring umbrellas and radial canals. Female gonophores have a bell-like shape with a single ovum surrounded by a network of spadicine canals. Male gonophores are sub-cylindrical and purple in color, and they include a central spadix.