What is the best thing about the marine core?

Well by the wording of your question, you must be talkin' 'bout those tasty treats in shells I like to call oysters. Or maybe yer talkin' 'bout clams. Love the clams....

The correct spelling is Marine Corps, which you might want to know if you happen to meet any Marines---they are quite fussy about honoring the Corps.

Their bootcamp training is considered the toughest of all military branches, but the PRIDE they feel when they make it through bootcamp lasts forever. If a Marine has been in battle, they tend to hold a lot of the trauma inside, not willing to give in to emotion (something that is part of their basic training), so you probably would need to be a good listener if you can draw them out at all. I think of the patterns they develop after being in battle to be very similar to the character "Spock" on "Star Trek," the half-alien/half-human mostly unemotional (but with a seed of emotion from his human mother's side)---Marines sometimes have this demeanor and have trouble with relationships unless the communication lines are open, because they hold a lot in and mainly only trust other Marines.

I keep telling you young folks that they are no different then anyone else. Yes their dress blues are nicer and thats it. Yes their basic is 4 wks longer but all that is, is more push-ups, sit-ups and running. You still have to do that when you go to your school / MOS anyway. I always ran at the end of the day and still do even after being retired. Big deal.

US Marine Corps :)

Past that don't know much past the history and they kick butt - forgive me I'm Canadian lol

The heart and lungs.

The fact that it's actually spelled "corp".