This is a marine worm, Dinophilus, and it’s parasitized by unicellular organisms called Grellia. You can see the parasites as blue, banana-shaped structures in this polarized view. . Dinophilus are a few millimeters in length and inhabit all marine environments. They eat algae and mind their own business without bothering anyone. However, the large population I had in one of my fishless tanks were all infected by a species of unicellular organism. . When I checked an odd-looking Dinophilus under

Christmas tree worm is the common name of a species of marine worm that lives in tropical coral reefs around the world. At the first sign of danger, Christmas tree worms quickly retreat into their burrows, hiding from potential predators. Here's a Christmas tree worm retracting in Mantanani Island, Sabah, Malaysia. #christmastreeworm #Mantanani #Sabah #Malaysia #Borneo #SabahWildlifeDepartment #SabahTourism #Scubazoo #SZtv | SZtv