Quote from Wilson:
Not sure if this was a glitch or not, but the first time I entered the Underground Tunnel (via Torvus Temple), I faced right and saw a Grenchler (Baby Sheegoth on crack) at the end, just hanging out and waddling around in the water. I grabbed the missle expansion and exited back into Torvus Temple. When I went back into the tunnel, the Grenchler was gone. Odd, huh? He's never been back yet either.