SPOILERS

The engineer that had it's head cut off by the door looks like an empty shell. The crew struggles to find anything inside said shell, as the dried body of an engineer is more or less a stringy mess of paper-dry mucus. And, because of the fluid-like state of an Engineer's real body, they can vary greatly in shape and size.

More or less octopus in terms of how they can squeeze through anything that their vital organs can safely pass through.

Now, they CAN still look like this:

But it takes effort and focus, and is mainly done to communicate to humans. And if communicating with another species, the Engineer tries to mimic that specie's face as well. I also imagine that the valves and pipes in their suit are how they communicate. Pushing water & air around to make whistles and hums. But when mimicking a species, they do form a copy of that species' vocal organs to speak.

Obviously a water-world derived species. Went to space, learned about heavy gravity and radiation, and manufactured suits that used minimal materials for maximum effect. Then went to design species after that blueprint.

I am (attempting) Photographing photos from all Na'vi camps and resistance field labs!

I imagine the Reef Na'vi have softer scents due to their lifestyle. As they aren't leaving scent lines while hunting/marking routes... That is to say, when the Sullys arrive at Awa'atlu, their scenting culture & scent strength must have been a little jarring.

Engineer being all to aware that while Shaw looks like him in a wide biological sense, she's far more fragile. Not due to her womanhood, no. But because she's human. Entirely non-biology modified for space travel. Where he can handle toxic air for days, she can't last seconds. Harsh cold has his blood producing natural ant-freeze where Shaw would die. When extreme heat cooks her alive, his in-built suit vents heat while retaining moisture... All this leading to over protection. He's aware that his living spaces fluctuate wildly in temperature, toxicity, and other issues. Where she needs a stable all-around living space. He agonizes over location the ideal location in his ship for her. Measuring everything he can think of. Radiation, light levels, micro organism populations on surfaces. He's working to hell and back- And then he finds her already settled. Having moved her things into a quiet corner that's on the opposite side of the wall as the main engine. The heat is perfect. The hallway has good airflow. The gravel floor is manageable with a few foam pads. She's fine.

(Yomvey is about to snatch them)

Did Tonowari teach him the sign for 'friend' in a past encounter? That'd be way cooler than him learning it via observing the Na'vi from a distance.

frfr tho he's reminiscent of both Grace + Trudy while remaining his own character! Openly admits to drinking the guilt away, and takes every chance they can to remind the sea dragon crew how fucked up the hunting they do is. And let's not even get into his heroics in movie 3!