It was a joke. You see, I was suggesting that a place with lots of sharks might be called "Shark", in keeping with the point of the original post.
I am aware that most shark attacks are due to mistaken identity, but it wasn't meant to be taken too seriously.
Perhaps the reason sharks came to mind before any other animals is because I read this article a couple of days ago: https://www.standard.co.uk/hp/front/surfer-bitten-in-half-7232230.html
It stands out because the way it was reported makes it sound like the sharks executed a coordinated attack on the surfer. But, again, I didn't expect to get cross-examined on what I intended to be a humorous remark.
Yes, but IIRC they just happened to be the location of the hell portal that humans disturbed, and hell started leaking out. The depiction of Phobos and Deimos as hell-like was after the leakage. The third part of original Doom was back on Earth when the leakage had spread there, and it looked exactly like the hell of the Mars moons.
I wouldn't bet money on that being exact, but that's how I remember it.