Flipfruit
A combination of intraspecific competition and predation drove a population of D. fruitflotensis to make a few changes. Though their ancestor floated about and used their long skinny tentacles to grab food, this proved troublesome as these were sometimes bitten off by predators or injured by rivals and even living “prey” they tried to grab through mistaken identity. This led to the flipfruit floating lower and using their shorter, less fragile arms to do so instead. This came with a few more benefits--signals from the brain reach them faster due to them being shorter, and the proximity to the mouth made eating with them much much faster. They also started to float less and move about on the seafloor more because this made them less out in the open and allowed them to find food more easily. This resulted in their namesake.
See, the flipfruit is upside-down compared to other helids. As none of its organs were dependant on their orientation, especially since its ancestor mainly floated and did not have eyes, doing this to adjust its locomotion had no downside. With their new position, its tentacles can easily reach forward and dig the claws into the sediment as it once dug into food, pulling itself along the seafloor as it floats slightly above; this also allows it to taste for biofilm and detritus on the seafloor far more easily, as it literally tastes it when it touches it. They can move surprisingly fast this way due to the length of the limbs involved, which helps in competing with rivals. Further, the new position places its anus, which was previously "above" its mouth and just off to the side, more below its mouth, so there is less risk of feces dribbling into its mouth. Its tentacles can still be used to feel up a potential meal, as they retain taste buds present in a distant ancestor.
The flipfruit has also developed simple “eyes” consisting of a light-sensitive spot of pigment and nerves on either side of the “face”, between the upper and lower facial limb on each side. These developed initially as spots of pigment which got warm as light hits them, and when their advantage was made clear nerve cells evolved to be clustered in the same spot to detect the temperature change. This allows it to detect predators when it suddenly goes dark so it knows to quickly withdraw into its shell; it distinguishes between predator and rocks, corpses, and other large harmless objects by the speed at which it goes dark. It also uses the "eyes" to detect when it's night time, at which point it sleeps because it won't be able to detect danger in the darkness. This increases its reproductive success for obvious reasons. They also developed brown coloration, stripes, and countershading to make themselves less visible to predators by breaking up its shape among the polyphs that reside in the same zone.
The flipfruit is otherwise pretty similar to its ancestor. From the back of the shell to the tip of the mouth limbs, it measures about 10-15 cm in length; this size comes out differently than its ancestor’s listed size because of the different, more intuitive measurement. It feeds on rotting organic matter, biofilm, detritus, polyph seeds, and carcasses. The polyph seeds it is known to eat include those of A. okeanus, M. aquatica, M. flotatortensis, and S. podius. This makes it a detritivore, a scavenger, and a base-consumer all in one. They breed in the winter and carry their eggs in their shells; hatchlings feed mostly on detritus and biofilm until they are big enough for larger meals such as seeds and carcasses. It has to deal with the same predators as its ancestor within the zone where it evolved.