Bacteria that form biofilms secrete molecules that they use to communicate with each other. These locally-produced molecules allow the individual cells to sense each other, a phenomenon called quorum sensing and, in this manner, coordinate their behaviors to perform activities that are required for biofilm formation. To form a biofilm, the bacteria adhere to a surface and aggregate, forming spore-like structures. This makes them very resistant to antibiotic treatments. This phenomenon illustrates the ability of the cells to: