The second stage in the second series of Phase Transitions. Compared with the previous stage, the crystals are growing and some more of them are showing up.
The circular dark spots on the lower left are probably bubbles of air enclosed between the surface of the heating table (a heat resistant glass coated with a thin layer of metal that can be heated electrically) and the cover slip.
Why are such structures beautiful? Let me share some thoughts from a comment I made, answering a comment to a previous post in this series.
I think there is a lot of unseen (potential) beauty in the microworld. I think structures with some mix of order and disorder have a potential of being perceived as beautiful (I have written about this in the article On Beauty before).
If you look at such stuff macroscopically, it would just be a whitish crust on the glass. It looks uniform and structureless.
Now if you zoom in, you would start seeing something like a texture, until you reach this scale where you have just a few crystals in the image, with some structure (like dendritic branching). On this scale, you have structure with order (crystals) and disorder (different sizes and orientations). If you zoom in more, you end up seeing just one crystal filling the whole picture, or a small section of it, so you have a totally ordered, boring picture again. So to a large extent, the trick might be just to find the right scale. Zoom in an out and at some point, there is a maximum of beauty or a potential of beauty because there is a mix of order and disorder.