Stromato-what?

Its called a stromatolite (stro’-mat-o-lite). It’s a fossil remnant of mats of cyanobacteria, also known as blue-green algae. The microorganisms grew in mats, bound together by slimy secretions that allowed entry of nutrients but protected them from environmental hazards. This allowed them to form three dimensional “microbe cities” that took knobby shapes. The top image…