Smallest Living Cell: Mycoplasmas are recognized as the smallest known free-living cellular organisms. Their size typically ranges from 0.2 to 0.3 micrometers.

Anaerobic Survival: These organisms completely lack a cell wall and are unique in their ability to survive in environments without oxygen (anaerobically).

Wall-less Nature: Because they lack a rigid cell wall, they are pleomorphic (can change shape) and are naturally resistant to antibiotics like penicillin that target cell wall synthesis.