They are bacterial colonies using silica to build mineral structures resembling stromatolites.

Stromatolites are some of the oldest forms of life that we can find on earth.

The oxygen exhaled by those stromatolites is what we all breathe today.

Stromatolites are the heroes in my story.

Learn to multiply, thickening in places ... Growing living structures under an alien sky ... Stromatolites were the first to exhale oxygen.

And their fossils are often preserved as layered rock structures, called stromatolites.

Now, what probably looks like a bunch of wrinkly old rocks are actually stromatolites.

Stromatolites in sentence