Giant snake
The giant snake was encountered by the Fishwives in a crumbling room in the Ancient Tomb. Sathul communicated with the snake, which appeased it. Ka-Ess killed a baboon, which was accepted by the snake as an offering despite the minor cave-in caused by the pistol shot. The snake did not attack the adventurers, but its disposition toward the Fishwives is still unknown.
It acquired a second head after the Fishwives awakened Xipacna, for reasons yet unknown.