Leonardo da Vinci said "Simplicity is the ultimate sophistication." I think The Eidolon is a good example of that. It's easy to over look the amount of time and work behind this short but well crafted animation.
The story is simple and straight forward, it's very carefully paced without unnecessary fill ups. The characters and environments design is simplified. The frame by frame animation is smooth while the line work stays clean. The voice work is also thoughtfully kept to minimum. I love your choice of color. (A little nick-pick by the way, I personally don't like the "black noses", it kind of distracting me from focusing characters facial expressions. I understand it's just a style, however, it looks much better with other skin color in your other works.)
Over all, The Eidolon gives me a good vibe of 90's sci-fi movies such as Alien and Event Horizon. In my opinion, it's a breath of fresh air among animations nowadays which fill with over-the-top effects and extreme humor.
May I ask what software did you use to create this film?