Well... I found the *ghost* of it here:
South of the Immaculate camp, there's a skull cave. Inside that is a bunch of portals. If you go into the ice portal and have perception of 11, you'll find the mound to dig up.
The ghost then tells you about finding its body, but I've been running around looking for it for an hour. So... yeah. Not doing so well on that front, but I'll update this thread if I find the darn thing.
