A milky-white, caterpillar-like creature about 5cm long. Size varies by individual; newborns are a few millimeters, while fully grown ones can reach up to 5 meters. It has snail-like tentacles. The front features a flower-like mouth, and the body tapers toward the back. It enters through human skin or mucous membranes using its thin rear section. Once inside, it is extremely difficult to remove until it has finished growing. When fully grown, it leaves the body (usually through an existing orifice, though it rarely bursts through the flesh). Since the parasite dies if the host dies, it learns to keep the host alive and avoid being expelled. It controls humans by sending signals to the brain, making the human act according to the parasite's will. Since a temperature slightly higher than normal human body temperature is optimal, it causes the body to heat up from the inside. Its surface is always moist to facilitate movement within the body, and it prefers slimy liquids.