P. fluorescens EvS4-B1 biofilms (21 days) contain macroscopic 3-dimensional structures. (A) Gentle disruption of the biofilm revealed a fragile mass of amorphous material connected to a parachute-like structure. (B) The structures were either well-defined packets (arrowheads) or aggregated flocs (asterisk) anchored to a fibrillary core (arrow). (C) The parachute-like structure was made up of 5 or 6 compartments. (D) Backlighting highlighted the fibrous nature of the parachute-like structure (arrow). Scale bars = 1.5 mm.