This slug like parasite is actually a symbiote. After attaching itself to a warmblooded host, it feeds off that being. However, its tenticles, growing under the skin, act as secondary nerves, increase the victims nerve responses.
These humanoids have flesh that resembles a peeled orange or other citrus fruit: semi-translucent with prominent veins. Brightly colored, some Rutaceaens are orange, some are yellow, and some green. They prefer warm climates with lots of rainfall.