What insignia represents an O-5 in the Marine Corps?

The insignia representing an O-5 in the Marine Corps is a silver oak leaf. This rank is known as a Lieutenant Colonel, and the silver oak leaf symbolizes the officer's level of authority and responsibility within the military hierarchy. Typically, military insignia are designed to denote rank clearly and effectively, with gold and silver elements often representing different ranks. For the Marines, the silver oak leaf distinctly identifies the O-5 rank, thus making it recognizable to those familiar with military ranks and insignia. The other insignia options represent different ranks: the gold oak leaf denotes an O-4 (Major), while the one gold bar represents an O-1 (Second Lieutenant), and the one silver eagle is associated with an O-6 (Colonel).