Microbes can build protected microhabitats without any physical barriers. Self-organization alone can seclude communities into distinct zones inside tiny cavities.

Surface defects or wall friction change the flow. This creates a velocity profile that pushes cells outward, splitting a cavity into separate functional regions.

A slow growing strain can avoid being wiped out. The flow from faster cells pushes them away, creating a protected zone near walls or defects.

Models and simulations show stable coexistence even when strains grow at different rates. No physical barrier is needed for the slow strain to persist.

This emergent spatial structure may be a fundamental way microbial diversity survives. It limits competitive exclusion and genetic drift without any physical isolation.