This video shows an individual of R. tagatzi abandoning its lorica, apparently in an attempt to escape an extracellular parasite. The latter (possibly the trophont stage) appears as an ovoid cell, featuring a delicate stem with which it fastens to the aboral part of the tintinnid’s lorica. A structure comparable to a feeding tube connected to the host’s cytoplasmic stalk is recognizable. In fact, all but one parasite reported to infect tintinnids are dinoflagellates (Coats and Bachvaroff, 2013), and the small ovoid cell does not look like any parasitic form so far observed (D. Wayne Coats, personal communication). An alternative explanation could be that a unicellular organism actually expels the cell proper of the tintinnid in order to occupy its lorica for its own purposes.
Any hint to solve this enigma will be the welcome.