Tube anemone retracted, Acontioid is the end of mesenterial filaments of Arachnactidae. The larva is Cerinula or Cerianthula,Sergio Stampar, Black Water diving over Gulfstream Current; Florida Atlantic Diving; Plankton; SE Florida Atlantic Ocean off West Palm Beach; larval fish; marine life; pelagic creatures; pelagic larval marine life; vertical migration marine creatures