Starblight
Starblight evolved from cobblebells that ended up infesting not only the rooted leafstars, but also their other relatives as well.
In order to spread itself and stay inside of its hosts, starblight has made drastic changes in both structure and reproduction. For the case of structure, it has evolved to take on three stages, spores, the free-floating sporelings, and the rooted adults. The free-floating sporelings resemble the cobblebell, although with a slightly more complex structure and black cell walls. These float through the ocean as they feed on decaying matter, which is supplemented by sunlight to some degree. Sporelings sense the enzymes released by the various infected stars as the means of seeking out a proper host to infest. Once the host has been found, the sporeling uses its claw-like apparatuses and probosces to cling and dig into the body. After doing so, the sporeling morphs into its adult stage by rooting inside of its host, growing a long, flexible structure supported by cell wall segments. These adult starblight no longer gain energy from photosynthesis as their chloroplasts have atrophied. Instead, starblight further exploits their expanded food source by feeding on their hosts’ cells. This type of diet causes its host to weaken due to a deficient immune system and hindrance to photosynthetic abilities cause the host to develop black patches at the sites of infestation. These types of symptoms typically lead to the host’s death, especially in older specimens.
As for reproduction, the starblight reproduces via budding while inside of its host, causing it to further spread inside of it. Another method of reproduction it evolved is the ability to produce new spores from tendrils that grow on top of the adult. These come off the parent and disperse through the water and waterlogged ground where they live as free-floating sporelings until they can come across new hosts to infest.
Starblight is currently restricted to warm, moist climate; thus, it cannot spread into polar environments or dry land.