It was a Cirolanid isopod of the order Isopoda. Cirolanids come in many different sizes and have a variety of diets. Most Cirolanids are indeed parasitic.
However, it is not uncommon for some species of Cirolanids to be just scavengers. In this case, this demon-spawn was attached to the bottom jaw of the larva; feeding off its soul. How did this parasitic terrorist get on my larva? It probably entered the rearing vat on the first day when I added the eggs/larva. This rearing vat was more of an experiment, so I wasn’t very cautious on what went in with them.
Fortunately, I was able to surgically remove the isopod and return the larva to the vat. I am not certain if the larva will make it or not; I can only hope. However, I definitely believe that it has a better chance than it did with the giant life-sucking monstrosity attached to its face.