Rhombozoa
The asexual stage is termed a nematogen; it produces vermiform (worm-like) larvae in the axial cell. These mature through direct development to form more nematogens. Nematogens proliferate in young cephalopods, filling the kidneys. Later, as the hosts mature, sexual forms called rhombogens are formed. They are hermaphrodites, with gonads of both sexes. The rhombogens self-fertilise, and later release larvae.