A Parasite, also known as a "HSP" (Human Scale Parasite). The Parasites are the secondary antagonists from Cloverfield.
Clover 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 "HSPs" (Human Scale Parasites). 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.