No blueberries that I can see at the Spirit site, but check out that shadow!

The microscopic pictures of this rock show no spheres. Still this rock has similar characteristics as those over at Opportunity’s site. What does that mean?

If it did form in a similar fashion, say a shallow sea, whatever conditions for the spheres to form over at Opportunity’s site did not happen here. That could be a chemical thing, or even a biological thing.

I think the water was deeper and fresher at the Spirit site than over at the Opportunity site.

There sphere must have something to do with the ancient environment of the Opportunity site. They can not be tektites, or we would see them at the Spirit site. Something in the environment, either chemical, or environmental, must have created them, and this environment was different than any other landing sites on Mars.