One of the things I believe is that most things are organized in the same manner the universe is organized. That is to say, everything within a scale works on the same basic algorithm as everything in every scale, and as you leave the scale, there is an unimaginably huge jump in scale.
For example, there are no moving creatures say, a mile long. Why? Because the materials creatures are made of won't support it. However, those materials are the materials used to create things on the clump of materials we call Earth.
Change the scale: let's talk about the clump of materials we call a galaxy. A galaxy isn't made out of "materials", really. It's made of star systems. Therefore, something which navigates the galaxy (a galactic 'animal') is unlikely to be made out of stuff related by a STRUCTURE, but more likely to be made up out of stuff related by ORBITAL PHYSICS.
You can also move down the scale: stuff made to navigate through materials is on a much smaller scale than animals to navigate a planet. They will be made of the stuff materials are made from, rather than from materials. Hence you have bacteria and viruses, made from molecules related by chemical bonds.
Of course, it stacks. An animal which moves across the Earth is, in fact, material. Therefore, he contains the potential for tiny organized clusters of "life" inside him. Therefore, those contain the potential for eensie-weensie organized clusters of "life", and so on and so on until you go insane. These things, of course, form the same kind of substance the larger creature is made of, in that clusters of cells are materials and clusters of animals/plants could theoretically be a planetary body.
I find this gives me lots of really bizarre ideas for games, stories, etc. Think about it: has anyone EVER written a story about a galaxy populated by starships which are actually STAR ships? As in a tight-knit bunch of celestial bodies orbiting a special sun?
Or going the other direction - what happens if you change the basis for the structure of life? Instead of cells formed by bonds between molecules, how about you suppose some OTHER basis? Like, say, instead of molecules, use chunks of emotion. All those old ideas - plant-monsters, energy beings, ghosts - they can be represented in new and interesting ways, with the various normal features of biological life replicated in a bizarre new fashion - one which holds together.
Of course, you have to build the physics on your own, but hey, life's good when you're building physics.
The interesting part is when you start to apply it to nonphysical things like, oh, economies. Or minds. Or memories.
What are those made of? What kind of creature can they form when glued together in great numbers? What does that mean when you project into the future with the assets you have?
For example: memories. Clusters of memories related by emotional bonds could form a kind of "mindcrete" which makes up a personality segment. What kind of physical interaction do these memories have? What kinds of mindcretes would you need? Replicate a life form's basic organs, but with clusters of memories. What kind of memory relationship forms a heart, pumping thoughts throughout to all the other mindcrete clusters? What kind of memories stacked in what way form lungs, breathing in new ideas?
It makes for a very interesting mind excersize, and produces some exquisitely unusual story ideas. :)