The Eagle, Globe, and Anchor [1] is the official emblem of the United States Marine Corps. The current emblem traces its roots in the designs and ornaments of the early Continental Marines as well as the British Royal Marines. The present emblem, adopted in 1966, differs only by a change in the eagle from the emblem of 1868. Before that time many devices, ornaments, and distinguishing marks followed one another as official badges of the Corps.

In 1776, the device consisted of a "fouled anchor" of silver or pewter. (A fouled anchor is an anchor which has one or more turns of the chain around it). The fouled anchor still forms a part of the emblem today. Changes were made in 1798, 1821, and 1824. In 1834, it was prescribed that a brass eagle be worn on the hat, the eagle to measure 3 ½ inches from wingtip to wingtip. This early insignia is found on the buttons of Marine dress and service uniforms today. During the early years numerous distinguishing marks were prescribed, including "black cockades," "scarlet plumes," and "yellow bands and tassels." In 1859 the origin of the present color scheme for the officer's dress uniform ornaments appeared on an elaborate device of solid white metal and yellow metal. The design included a United States shield, half wreath, a bugle, and the letter "M." In 1868, the Commandant of the Marine Corps, Brigadier General Jacob Zeilin appointed a board "to decide and report upon the various devices of cap ornaments of the Marine Corps." On November 13, 1868, the board turned in its report. It was approved by the Commandant four days later, and was signed by the Secretary of the Navy on November 19, 1868.

On June 22, 1954, President Dwight D. Eisenhower signed an Executive Order, which approved the design of an official seal for the United States Marine Corps. The new seal had been designed at the request of the Commandant of the Marine Corps, General Lemuel C. Shepherd, Jr. The new seal consisted of the traditional Marine Corps Eagle, Globe, and Anchor emblem in bronze; however, an American bald eagle replaced the crested eagle depicted on the 1868 emblem, and is depicted with wings displayed, standing upon the western hemisphere of the terrestrial globe, and holding in his beak a scroll inscribed with the Marine Corps motto "Semper Fidelis" (Always Faithful) with the hemisphere superimposed on a fouled anchor. The seal is displayed on a scarlet background encircled with a Navy blue band edged in a gold rope rim and inscribed "Department of the Navy, United States Marine Corps" in gold letters. Coincident with the approval of this seal by the President, the emblem centered on the seal was adopted in 1955 as the official Marine Corps Emblem.

Info obtained from Wikipedia