Daggerback
Under pressure from numerous predators in its environment, the thornworm selected for greater defences, with the new organism replacing its old form. These defences came in the form of absurdly large knife-shaped spines derived from the spikes of its ancestor, which make it much harder for predators to grasp or consume it. The underside of its shell has formed into out-pointing spikes to bolster its defences further. It has mostly abandoned the harsh abyssal floor in favour of the more oxygenated abyssal slope. Due to living in the bleak, infinite darkness of the abyss, it has lost its ancestor's photosynthetic abilities.
Due to a lack of usable senses that the organism could use to sense its environment, it has developed 2 pairs of feeling tendrils that allow it to feel its way around the world. Its newly developed legs are highly mobile and flexible and are capable of sticking to the floor, making it even harder to consume. They function through the use of a hydraulic system, with chlorocruorin-based blood being pumped into a limb to inflate it for movement, before being pumped back out when movement with the limb is no longer needed. Muscles at the top of the limbs close when blood fills them, preventing the creature from bleeding out if a limb is severed or severely lacerated.
Being an obligate scavenger, the organism uses its feeding arm, which tops off with a number of crystalline spikes, to scrape edible material from carcasses and place it into its tube-shaped mouth. Due to its low energy lifestyle, it is able to survive for long periods of time without consuming anything. The daggerback is typically found in large groups around carcasses, scavenging and breeding.