It indicates this coin is in the Rocks In Cages cache, but I did not find it there. Interestingly enough, I did find a pin in the cache with a trojan helmet on it, though! :)
Here is a quick note that will be helpful in showing you how to mark your trackable as 'missing' for now: http://support.groundspeak.com/index.php?pg=kb.page&id=152
This entry was edited by SylverWinged on Sunday, 21 July 2013 at 22:21:43 UTC.