Final answer:
The outermost layer of some bacteria is known as a glycocalyx, which aids in adhesion, biofilm formation, and provides protection for the bacteria.
Step-by-step explanation:
In some bacteria, the outermost layer is a gelatinous sheath known as a glycocalyx, which can also come in the form of a capsule or slime layer. This cell envelope structure allows bacteria to adhere to surfaces, aids in biofilm formation, and provides protection from predation and environmental stresses. The glycocalyx is usually composed of polysaccharides or proteins, and while capsules are highly organized and firmly attached to the cell wall, slime layers are less organized and loosely attached.