Yes, they are part of another puzzle. You can read which one in the guide (http://www.ldwforums.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=53354&page=1#Post53354). But if you want to know right now, start highlighting here: When you have uncovered the ruins, if you place a totem in the center of it on top of the yellow circle you'll get a piece of the Gong. End highlighting.
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And what if it makes you laugh now but you cry as you fall asleep?