sharks and serial suicide

I’m walking on the border between huge fishtanks. Enormous sharks (whites?) follow me closely half a meter below. Although their eyes are black, I can clearly read them : “If you lose your balance, we’ll tear you apart”.
One of the sharks has long scars on the top of its head, like it’s been mangled by a boat.

Then I’m safe and I enter the building next to the fishtanks.
Suddenly I’m no longer part of the ’story’. I see what is going on behind the closed door of a toilet cabine. A man tears the head off a woman he just killed. He hands it over to another woman, who’s sitting on what seems a cupboard. She has the exact same face as the head she’s holding(twin sisters?).

She looks at it without emotion while she washes off the blood of what seems to be her own face.
Then I see her completely. Beneath her ribcage, all flesh has disappeared. I can see her intestines working, her spine flexing as she repositions herself.
I wake up, still wondering how it’s possible she’s still alive.