Answer: Resemble structures formed by bacterial colonies found today in some shallow marine bays
Step-by-step explanation:
Stromatolites are laminated accretionary structures that have synoptic relief (i.e., they stick up above the seafloor). They grow in extremely salty shallow lagoons or bays. Stromatolites building community includes the oldest known fossils.
They are formed by bacteria such as cyanobacteria.
This is why they resemble structures formed by bacterial colonies found today in some shallow marine bays.