By far, the strangest reef inhabitants are dodecablobons. They are made of twelve, semi-autonomous, worm-like bodies attached in a row to a common trunk that allows them to share an oxygen circulatory system (some are also capable of sharing nutrients). Some bodies are predators, others herbivores, others filter-feeders, others decomposers and detritivores, others parasites, and others contain symbiotic photosynthetic or chemosynthetic monocells. Some have gills and some have lungs (they will on occasion wander onto shore or float on the surface when the water becomes polluted by excessive monocells). Any one of them can go dormant and accept a protective mucus secreted by the central mass to prevent drying, abrasion, or damage from extremes of PH. This makes them extremely versatile and able to adapt to different habitats. The central nervous system operates on a "rotating presidency" principle. Each of the twelve members of the symbiosis takes turns at control of the central mass and locomotion of the creature, while the other eleven retain control only over themselves.
Some dodecablobons’ member bodies grow all the way around the central trunk and so resemble the segments of a worm.
One dodecablobon that resembles a segmented worm is the rhinoceros fern fish. The first segment forms a rhinoceros-like head, the next seven segments each have two lateral swimming fins, and the last four segments form a distinct, tapering abdomen with four vertical fins above and four vertical fins below. The horn is used to break free reef-building animals or weeds so they can be sucked into any one of its twelve mouths. Some of the other segments have horns as well. It is among the most colorful and most rare of the reef’s inhabitants.