When you say "just salt" ... what kind of conditions produce that sort of salt formation? Does it tell us anything about the conditions when it was formed? Was there some brine pool or something? How did it get exposed where it is now?

Maybe describing it as "plant-like" was not really called for, can we still learn something interesting from this?

There’s always something cool to learn about geological processes, even basic examples like this one.

I too am wondering if 'salt sculptures' implies there was salt water at some point.

I have no idea. But can imagine that another proof of water, salt even, is really nice.

There was very definitely large* amounts of water on Mars, and there is also evidence of salinity[1], so it seems possible that there would be saline in volume to produce deposits.

* - not compared to Earth, but more than you would think from looking at the surface - https://en.wikipedia.org/wiki/Water_on_Mars

[1] - http://nature.com/articles/doi:10.1038/ngeo2546

My first thought was some sort of crystal formation. Not sure if it's salt but it does look crystalline in nature. I'll get off my exogeologist armchair rest now.