Various, rarely observed biofilm structures such as crystals, granular materials and fibres on the air-exposed contact lens surface after 72 h growth. Extensive agglomerations of bacterial cells were found to adhere to the surface of crystals and granular materials. Crystals and granular materials were also associated with the formation of fibres. Acridine orange staining of the fibres verifies the presence of bacterial cells throughout the fibres. Bar = 20 μm.