Underbelly Diaminet

The Underbelly Diaminet split from its ancestor. It has taken the mostly unclaimed niche of feeding on organic matter on the “underbelly” of the Driftwood Islands, as such increasing significantly in size due to lack of competition. It no longer floats at the surface of the ocean, instead reaching buoyancy in the twilight zone. It naturally floats upside down as a “sapling”, its roots rising above instead of dragging below. After living as roughly 10 centimeter tall plankton for a time, it eventually takes root on the underside of a floating island, consuming any organic matter it can reach. Its waste is released into the ocean; this would seem to imply that its influence would make the islands shrink down and eventually sink, but on the contrary, it actually shifts the ratio of sinking and floating matter in favor of what can float. As it grows, the Underbelly Diaminet becomes less dense in order to push itself upwards and deeper into the underbelly, which makes it more difficult to dislodge and also helps keep the islands afloat. It is now hexaradial instead of tetraradial.

The Underbelly Diaminet no longer forms symbiosis with floating flora, as they cannot survive in the dark depths. It gets all the nitrogen it needs from its food instead. It is only a predator as a “sapling”, losing its numbing toxins in adulthood. Mature Underbelly Diaminets are connected to their neighbors by special roots which grow from their corners. They transfer nutrients throughout the colony, keeping all parts healthy so that they form an unbroken net supporting the entire island. In addition to this trait simply being inherited from their ancestor, they must do this to survive and keep their food source intact, as older, thicker islands may be dependent on the crystals to stay afloat. If a large portion of the colony dies off, it can destabilize the island and cause it to sink or break apart, which can wipe out the colony.

Like its ancestor, the Underbelly Diaminet reproduces using waterborne spores. Colonies are often genetically diverse and made up of many unrelated individuals, as it is very rare for an individual’s offspring to take root anywhere close to its parents. Saplings which are ready to take root will grow out their net-roots, “reaching” for established colonies. The sapling net roots are very long and can physically prevent it from settling in a location where it has no space to reach full size. Once the sapling takes root, the net-roots will connect with those of its neighbors, and unused ones will shorten and stiffen, only extending again if they touch a new neighbor’s net-root. The optimal colony would have all members arranged in a tessellating, honeycomb-like pattern, but this is very rare; most colonies just look like tangled messes. The shortening method for the net-roots can also be used with the feeding roots, allowing colonies to slowly rearrange into a more stable pattern by having the members move in certain directions based on hormonal cues.

In addition to growing on the Driftwood Islands Underbelly, the Underbelly Diaminet can also grow on the undersides of so-called “rogue islands”, giant floating islands which are not a part of the Driftwood Islands landmark. Though the climate on the surface of rogue islands is too variable to support permanent biota, even the grasses that built them swiftly dying off when they drift into polar waters, the temperature of the mostly twilight-depth underside remains the same, allowing the Underbelly Diaminet to survive and keep the island intact without its original builders being present.