Cephalothrix sp. (Nemertea, Palaeonemertea, Cephalothricidae), pilidium larva, hight 400 µm, Helgoland 04.2015. 0:31 min. The taxon Heteronemertea in the taxon Nemertea or Nemertini develops characteristic planktonic pilidium larva (pilidium: form of roman helmet) with fore-lobe like a baseball-cap and hind-lobe, at each side lateral lobes, all equipped with ciliary bands. The mouth is located between these lobes. An apical plate near the top bears a tuft of long stiff cilia. Video can be used for teaching.