Crystals of a sublimed salt.
This is a quite special compound what was made months ago. It was placed in another lab in a small vial and from the heat of sunlight it sublimed on one of the walls of the glass. Why is it special? It’s a salt, like sodium chloride, only difference is, that it has highly fluorinated, fluorous side chain that makes volatile, so it could be distilled/sublimed to produce nice crystals as on the picture.
Want it on your wall? Print it out and use it as you want: http://imgur.com/N6SR9YW