Interesting spherical/ball shaped object caught by Curiosity Rover, and as the video suggests this could be proof of past marine life on the red planet.
Although they may look plant-like, sponges are the simplest of multi-cellular animals.
A sponge is a bottom-dwelling creature which attaches itself to something solid in a place where it can, hopefully, receive enough food to survive.
As we know nature does not create perfectly round rocks, so this indicates the object is either manufactured, or in this case the possible fossilized remains of a sea sponge.
If it is a sea sponge, then this proves that Mars did have oceans and had an atmosphere capable of sustaining life.