Water-collecting tubes converge into one apical osculum. The size of the osculum is regulated by contractile myocytes. The osculum is encircled by oscular fringe. The osculum at the tip is fringed with fine spicules. There is an osculum at the apex of the sponge. The free end of each cylinder communicates outside by large osculum. During spawning, sperm burst out of their cysts and are expelled via the osculum. At the tip is an osculum fringed with long, upright spicules. The pamphlet provided the first descriptions of the "osculum infame" to the English population. Some species can contract the osculum independently of the rest of the body.