Marrowbreach

Adapted to shear through tough, plasticized flesh. Edged in iron and salt tesserae. Bites deliver thousands of newtons of force in sixty milliseconds. Beware of pre-attack behaviors such as circling or test bumping.

Optic nerves connected directly to the jaw muscles—probably for bite timing. May be distracted by bright lights.

Body lined with neuromasts and gel-filled ampulae to detect motion and electric fields. Sensitive hearing. Aware of prey before they are aware of it.

Large caudal fin and muscular peduncle allow for sudden lunges. Squalene-rich liver provides buoyancy control. There is no thruster; the marrowbreach swims like a conventional fish. Assessment: apex predator. Avoid or distract. Investigate long-term possibility of mutual association through cleaning/feeding, but remember that this is a wild animal.