Fig. 4. A: Countless clusters of biofilms showing typical growth phases in which colonization and polysaccharide matrix formation occur (×1000). B: Biofilms were well attached to the irregular surface of the magnet. Biofilms grew and matured to form towers stacked in layers (×5000). C: Biofilm clusters showing evidence of stacked towers and water channels (×15000). D: Under the cracked plate-like biofilms, tower-like three-dimensional structures formed numerous holes and water channels (×15000). The region in the white d box is magnified consecutively from A to C and D.
