A Difficult Mystery (Part 2)

Here's the recap. Our first clue was really tough. 

Let's get closer and see if it helps!

I can see it here, but I know where and what it is, so I have a huge advantage! I think it's still almost impossible otherwise... But you have all really surprised me in the past, so I know you have sharp eyes.

Don't forget that you can enlarge the picture by clicking on it.