When I first saw the image that sparked all this, I myself thought it was suggestive of many different possibilities other than what it was in reality. These included just about all that others have mentioned, plus a few from other realms.
Let's talk process first. The original material here went through repeated cycles of melt and "freeze" (solidifying, anyway) with resultant separation of some of its components...it was not, in this case, an aqueous process, as the component with the lowest melting point was a fat, but I, too, have seen similar patterns in the topography near springs and seeps, both where they emerge to the surface from rocks and where they emerge underwater. I've also seen it (though I can't pin down the year I saw this image) in an article on metallurgy, where two metals were melted and improperly cooled or reheated or something. I've also seen similar surfaces in rock, especially--as the whole image shows--areas of concentric ring formation.
This solid was also improperly melted, cooled, and remelted, while not moving (it was an accident...) with this fascinating result.
And here it is:
A high cocoa content chocolate bar, left in the car by mistake for several weeks, and suffering repeated cycles of melting and cooling. The cocoa butter and solids separated.
And it still tasted good.
We have a clear winner in the "closest to right" category, and she will be offered a choice of available prizes. True, she used a clue I hadn't meant to give, but fair's fair. As for the other entrants--several of you did excellently and I've got to rummage around and see what's available.