SCP-939 are endothermic, pack-based predators which display atrophy of various systems similar to troglobitic organisms. The skins of SCP-939 are highly permeable to moisture and translucent red, owing to a compound chemically similar to hemoglobin. SCP-939 average 2.2 meters tall standing upright and weigh an average of 250 kg, though weight is highly variable. Each of their four limbs end in four-fingered claws. The jaws of SCP-939 are lined with red, faintly luminescent fang-like teeth, similar to those belonging to specimens of the genus Chauliodus, up to 6 cm in length, and encircled by heat-sensitive pit organs.