With the rise of bigger predators, a group of predestars split off and developed new features to help them along. The horrorstar is noticeably more active than its ancestor; its left, right, and anal arms have been modified for swimming, with the fingers on the latter taking on a tail fluke shape. Simple gills have formed from its chemoreceptive patches, the insides lined with modified cellularized baits which absorb oxygen as water passes through them—all to support the more active lifestyle. Its mouth has been modified as well, now being lined with cutting keratin spikes—when it inverts its mouth into a stomach to feed, the spikes hold the food in place, and the suction from the action even allows them to tear through flatter surfaces such as larger fauna or flora. It has developed a pair of mobile spikes from these as well, which further close off the mouth as it eats. It now makes use of digestive enzymes to partially break down the food before it is absorbed into its cells, making its eating more efficient overall. It has also gained simple pigment cup eyes so that it may see predators and avoid them.
With its anal and side arms becoming fin-like, the horrorstar began to use its front limb as a grasper to peel stickerstars and the like off of surfaces to eat. However, its food source has expanded beyond asterzoa thanks to the changes in its mouth. With the combination of suction and cutting spikes, it can now tear holes in much larger fauna and flora, letting it prey on fauna larger than itself; it is functionally parasitic to fauna too big for it to kill in one bite. With all the food it gets from this, it has lost most of its filter-feeding baits, only retaining some on its side arms to help shape them. It digests the harder bits of worms and crystal flora, the latter of which it can consume by biting at edges and corners, with help from melter detritis which live in its mouth.
The horrorstar has also developed a simple “pelvis”, an internal ring of cartilage which its limbs attach to via muscles; this makes motions such as padding much stronger while using less energy, helping it to both catch prey and avoid predators. Its mouth muscles attach to this as well, allowing it to grab prey with more force. Its subdermal musculature has advanced into a muscular abdominal wall, a shared trait with its cousin Grazestar, granting it a proper coelom.
The horrorstar is otherwise much like its ancestor. It reproduces sexually, mating with any individual it comes across with 50% success. Though fin-like now, the three fingers on its anal arm still help it hold on during mating, ensuring successful fertilization. Like its ancestor, babies develop inside the mother until they are developed enough to swim right out. Newborns are radially symmetric and lack the mobile spikes on either side of the mouth, becoming bilateral as they mature and their arms start to differentiate. Due to its increased complexity, it is no longer able to reproduce by fragmentation and it must mate.