what is this icon?

I think I might have asked this before and got an answer but I can't find it!  Hidden City, Temple of the Sun.  In the annotated map there's an icon which isn't present in my map.  It's vaguely octopus-shaped, with really short tentacles, under the "T" of "TS", with 12 sort of WNW and 13 further away to the SE.  I did this tomb/thing and it's not showing up.  I have a vague memory that it shows up on PC but not on Xbox.  Well, maybe that vague memory stems from it not being on the screen right now.  Maybe it's something that appears later, it's quite a while since I did the game so can't remember!