The Anchor in the Marine EGA Emblem is a fouled anchor. (Rope around the hook)
In Boot camp, we were told it’s because Marines suck at being sailors. True or not? who knows.
In the meantime, last one out, close (or shut) the hatch behind ya. And if you’re in the way, gangway, make a hole.
Make a hole, or become one (submarine phrase)
Old habits you know. I would've sucked at sailoring. Fortunately, they had helicopters.
For fouled anchor tradition you can blame the Royal Navy. 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. His flag: 
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
Then, please, if the fouled anchor means that Marines “suck” at seamanship, what is the symbol for the USN Chief Petty Officer?