Moloch (Barotrauma)

The Moloch is a very large, ponderous, jellyfish-like creature found within Europa's vast oceans.

Biology
Molochs bear a resemblance to an extinct Earth creature known as Dollocaris: their main bodies are covered in an armored shell with several tendrils hanging from the body to navigate their surroundings as they have very poor eyesight.

Behavior
Interestingly, these creatures are dangerous to expeditions, but not directly towards divers as they tend to focus their attacks on approaching vessels. This is possibly due to misidentification for another Moloch or a larger predator, and they could be doing this as a defensive tactic to drive the threat away.

Molochs are very vocal creatures, and are capable of emitting a surprisingly varied amount of tuneful notes, which vaguely resemble the calls of Earth whales. These calls have even been known to reach infrasound levels, and some expeditions have mistaken their presence for alien artifacts within alien ruins.