UNAUTHORIZED FUCKING THING

man mogging and next thing he goofy

The eel was originally MUCH bigger in the concept art than the movie. I think it's implied she's massive, and she was intended to be massive, but having something that big would have destroyed the beautiful camera framing, so they toned it down and made its face look more like a human skull:

The Eye presenting the Eel's severed head to Simon like a dragon it just slew for him?! Hello?!

ALL the eye concept art iterations. My god, I cannot imagine the time it took to do all that.

The human spine and shoulder blades in the Eel's face, just haphazardly congealed in the meat, ribs poking out of her jaw like little baby teeth. Insane.

The eel was injured by the Anomaly (we can hear her screaming in the movie), so we can assume that Simon getting vaporized was not a hallucination. He did not hallucinate any of that. It was real! The whole rest of the time that fight is going on, she's half-cooked. You can see that continuity in the art while she's chomping down on the sub! Meaning, Simon really did truly die and come back to life.

Simon actually took pictures of the damage on her face:

Furthermore, the LIGHT coming from the sub that we didn't get to see well in the movie; HELLO?! The last thing Simon saw was a flash of light. Where did it come from? The pendant, which crackled that same blue-ish color in the scrapped storyboarding scene, maybe? Horrendous knowledge has been bestowed upon me. There was more to that pendant than meets the eye.

The roots you see growing up over the camera in the last few shots of the black box data are not just growing onto the eel. They're going INTO the Eel. Literally shot through her body and rooted into her flesh while she was still alive. What an awful, horrible way to die, for both individuals.

The Blood Tree is using the Eel's corpse as a damn plant starter. It's eating her. She's fertilizer.