Hedgestar

With the rise of predators, a population of grazestars split off and developed a defense. The hedgestar is rather round and stands lower to the seafloor compared to its ancestor, completely losing the ability to swim in favor of using its limbs exclusively as legs. Its back is protected by keratinous spines—essentially a growth of its existing mouth bristles on other parts of its body, which are also greatly enlarged for defense. Unlike its tripodal ancestor, the hedgestar is a quadruped—as keeping the anal arm on the ground makes it less susceptible to being grabbed and bitten off by a predator. In adulthood, it lacks digits on any of its limbs except for its anal arm.

Like its ancestor, the hedgestar wanders about the seafloor feeding on rooted leafstars. Due to its increased size, larvae are better able to feed on rooted leafstars as well and have lost their filter baits; however, bizarrely, they still filter feed in eggs, as the eggshell, which like the ancestor's is made up of living cells, is itself covered in filter baits. This allows hedgestars to have more offspring without expending as much energy forming the egg—the yolk supply, which is connected to both the shell and the embryo, is simply replenished by the eggshell as it captures and consumes microorganisms. This also allows hedgestars to have lots and lots of babies; each successful mating can produce as many as over 200 eggs.

Like its ancestor, the hedgestar mates by linking anal arms together. They cannot distinguish between male and female and simply mate with any individual they come across with a 50% success rate. Their larvae are radially symmetric and lack protective spines upon hatching, but the spines are among the first adult features to develop as they eventually turn bilateral.