NASA's "astrobiological discovery"

Last Week NASA teased the world with what it called a "major astrobiological discovery".  NASA merely said (via a press release) that the definition of life had greatly expanded.  They introduced a microorganism that had cell components that were based off of Arsenic instead of Phosphorus like every other organism we know.  They said that they were "Conducting tests in the harsh environment of Mono Lake in California" when they first found the microorganism.

However, the more I think about this, the more this idea bothers me.  Microorganisms based off of Phosphorus have evolved into new and different creatures. So why haven't these organisms based off of Arsenic evolved?  You might argue that the Phosphorus creatures have been around for a longer time then the creatures based off of Arsenic.  However, if that is true, then the Arsenic organisms must have evolved from a creature based on Phosphorus.  How is this even possible? They must have been created (whether you believe in the Big Bang or God) at around the same point in time.

So where are the other organisms that are based off of Arsenic?  I believe that they are in space somewhere.  There have been reports of a Perseid Meteor flying over Mono Lake in August (You can see a picture here).  Maybe something fell of that meteor. 

Now let's look at the wording of NASA's announcement.  They said ASTRObioligcal discovery, however this discovery should be categorized under biological.  That is unless, NASA was hinting at something.  I believe that they were hinting at the fact that this they suspect this microorganism is not native to Earth.

With NASA's announcement, I feel that it did not help our understanding of Earth at all.  In fact, it just showed us how little we really know about Life, the Universe, and everything.