The monster was covered in 2,000 Parasites that are roughly the same weight and height as a dog. They have 10 legs consisting of six spider-like, double jointed limbs and 4 "pincers" on the top and back of its body. They have very large jaws, pale gray skin and multiple black eyes.
The Department of Defense codenamed the parasites "HSP" (Human Scale Parasite). The Military notes how the parasites attack in pack coordination and prefer enclosed spaces for trapping and surprising their prey. They can also detect unsuspecting victims from afar, by an unknown method. The parasites are also suspected to be the reason the monster made its violent emergence from the water and onto land.
A dead Parasite (tagged "Specimen #94P") was a key component in the Department's research in the physiology of the HSP. A yellow substance around its mouth was initially thought to be a sort of venom; however, further studies indicate that it may be a form of saliva.
The Parasites have concentrated levels of Katei no Mitsu in their blood, a key ingredient in Tagruato's Slusho! beverage. One theory is that water poured onto a Parasite causes a reaction in the Parasite's saliva that accelerates the degenerative process in the HSP's victims; The life span of a victim varies between 20 or 40 minutes. Moments before death, victims of Parasite bites exhibit symptoms of dizziness, bleeding from the eyes and nose alongside vomiting blood.
Their bodies expand and the central cavity explodes outward. Marlena Diamond and a soldier being carried out on a stretcher died in this manner. Isolation of victims in their final moments are a precaution against initial fears of viral contamination. The rapid containment of their bodies before inevitable combustion is also necessary for hygienic purposes.
The parasites' movement is unique in that they have the ability to climb walls and cling onto ceilings. Their leg movement is similar to that of spiders, and have the ability to jump great distances.