SCP-150 resembles Cymothoa exigua (tongue louse), but is adapted to Homo sapiens. Upon contact, the subject embeds itself deeply in the flesh of its host. Within 48 hours, the limb nearest to the infection site will have been converted to a chitinous exoskeleton-like appendage. The exoskeletal limb is composed entirely of matter consistent with SCP-150. The host is capable of controlling this limb as a normal one, due to an advanced neuromuscular interface between the parasite and the host. The parasite draws nutrients from assimilated blood vessels, primarily the brachial and radial arteries in the arms, and the femoral artery in the legs. Stage 2 of infection begins approximately 7 days after infection. Hosts report sensing an unfamiliar voice, urging them to act in a way that will result in the loss of the parasitic limb. Upon detachment from the host, the appendage acts much like a shed exoskeleton. Multiple parasites emerge from this "cocoon" and seek out the nearest host, thus continuing the cycle. In ██% of cases, the hatched parasites return to the original host. This will continue until all of the original host's limbs have been infected. Once all of a host's appendages have been infected and detached, multiple instances of SCP-150 will burrow into the host's torso. These specimens will attach themselves to the pulmonary artery, the aorta, and the carotid arteries. The host's chest will swell to ███% of its original size. At this point, between ██ and ███ specimens of SCP-150 will emerge from the host's chest cavity. Stage 3 infection has a 100% fatality rate.