Here's a basic biology-101 lesson, Robert.

Vipers, rattlesnakes, etc., are able to 'see'/locate their
prey in the IR (infrared).
End of biology lesson.

The color filters on the cameras on the Mars rovers have
IR filters on them.

IR filters on colors cameras are IMPORTANT...for science.

With IR filters you could tell if there are deep layers of dust
or thin; you could tell if it's a solid rock; or something
resembling pumice.

In other words?

You have as much chance of seeing 'real' blueberries in that
martian bedrock as you would of seeing blue-green algae.

Jacob

"EXTRAORDINARY claims require EXTRAORDINARY evidence."
CARL SAGAN