Board Thread:General Discussion/@comment-26581304-20151213220153/@comment-24577221-20151213233042

In the first release of the game, one of the Skylite crystals could be hidden on a ledge on the "battlement" at the left edge of the island, completely impossible to see. That's no longer done.

Once the water land has been revealed at level 30, it's possible for an Aqualine crystal to be hidden on the little ledge under the wooden arch just below the thing that looks like a volcano. It can be seen, from the correct viewpoint, but it's a bit tricky to spot it.