These have spines along the inside edge to assist in securing prey. Seven pairs of jointed clawed appendages run down the sides of the mouth. The mouth appears to pass food directly into the creature's stomach, with no real throat structure present.
The creature's mouth is located on its underside just behind the head: it is a glowing blue tone, and lined with curved teeth resembling a ribcage with the sternum removed. The creature possesses a flexible spinal cord allowing it to contract and retract its head. The head is composed of a triangular shield-like structure with three pairs of small black eyes and a large red ring in the center. Below each row of red spots is a shorter row of eight circular gill pores that run down the side. The Shadow Leviathan has an elongated black body with smooth skin and twin rows of 37 small red spots running from behind the head to just before the tip of the tail.