The history of the fouled anchor dates all the way back to the original seal of Lord Howard of Effingham who served as Lord Admiral of England during the defeat of the Spanish Armada in 1588.
The Lord's fouled anchor consisted of a standard nautical anchor with a rope looping through the structure.
Lord Howard of Effingham fouled anchor.
The U.S. adopted the iconic symbol from the British in the late 1800s for Naval Chief Petty Officers to wear as it represents the trials and tribulations they are forced to endure on a daily basis. Chiefs regularly serve as the "go between" for officers and junior enlisted personnel.
The adaptation consisted of adding the U.S.N. to the anchor, but these letters which aren't referring to the branch of service like one might think — United States Navy.
The "U" stands for Unity as a reminder of cooperation, maintaining harmony, and continuity of purpose and action.
The "S" meanings Service, referring to our fellow man and our Navy.
Lastly, the "N" refers to Navigation, to help keep ourselves on a righteous course so that we may walk upright.
The U.S. Navy's fouled anchor
Earning a rank of a chief (E-7) comes with several years of dedicated service, an intense selection process and be eligible for promotion from the current rank of Petty Officer First Class (E-6).
The Navy has four different chief ranks.
The Navy rank insignia of a Chief Petty Officer - E-7 (left), Master Chief Petty Officer - E-9 (middle), and Senior Chief Petty Officer - E-8 (right). (Source: The Goatlocker)
The fourth chief rank refers to the Master Chief Petty Officer of the Navy or MCPON. Only one enlisted Master Chief Petty Officer can hold this position at one time — they're the most senior enlisted person in the Navy.