I already posted a topic on the "H" word: Halophiles.
To regurgitate, halophiles are extremophilic bacteria
that can survive in highly saline water [upto 30 percent salt],
maybe even in brine too.
Halophiles have been found in the "Dead Sea, Great Salt Lake, etc...

OK! It's obvious what the connection is to yesterday's JPL news conference.

You've found hard evidence of liquid water [SALTY OR ACIDIC] on Mars, you've
found conditions for halophiles, or oxophiles [acidic water bacteria],
to exist in....maybe a billion years ago, a million years ago, maybe even TODAY.

I like Marcia's geo-historical approach to this topic, I'll try something similar....

In that area of Meridiani there are abundant sulfates like jarosite.
The jarosite probably formed in acidic water [H2SO4 + H20].

So here goes...A billion or two billion years ago, Meridiani contained lakes or pools
of acidic water, acidic molarity unknown. ->

(1) Oxophiles could have existed in that acidic water. ->

(2) As years and centuries went by, the acidic molarity of that acidic water DROPPED
as H2SO4 in the water reacted with certain minerals and iron-rich deposits in
and around those bodies of acidic water. ->

(3) As the acidity of the water DECREASED over time, the SALINITY subsequently increased. ->

(4) The oxophilic bacteria may have evolved/mutated strains that were halophilic
as the salinity increased. ->

(5) Evaporation and much later, sublimation, dried up those lakes and pools, leaving salt-rich deposits
that formed sedimentary layers by concretion. ->

(6) Finally, volcanic dust, rich in olivine, drifted in and gradually buried the salt-rich layers of bedrock. ->

(7) Boom! A meteorite exposed the salt-rich bedrock where Opportunity roves today.

How am I doing?

Jacob

"This planet has a 100 percent mortality rate."