Among material coming from Hercegovina some living trochoporae of the cave Serpulid Marifugia cavatica have been found. In the laboratory of the Biology Institute of Ljubljana the further development passing stages of metatrochophore and nectochaeta have been observed. The constitution of the trochophore is typical. The nectochaeta possesses three metamera and each of these has only one pair of setae. The nectochaeta once it gets attached to the bottom the neck and beginning of tentacles are beginning to develop. The tube, three pairs of simple tentacles and the opercula are formed in further stages. For the period in which the tube is short and completely adherent, the animal reposes on the substratum with its dorsal side.