Squatting in a dark cavity in the side of the tunnel was a disk-headed furred animal the size of an elephant. It was clearly visible in the infrared of its own body heat. Afriel could hear it breathing. It waited patiently until Afriel had launched himself past it, deeper into the tunnel. Then it took its place in the end of the tunnel, puffing itself up with air until its swollen head securely plugged the exit into space. Its multiple legs sank firmly into sockets in the walls.