Above are two bodies, constrained together relative to their centers. After stumbling on a roughly 9 minutes video about procedural animations and simulating biological movement, I wondered if I could turn a couple sentences into actual working code. This being the first step of that process.
When two bodies are constrained at a distance an interesting behavior is observed where the larger body takes precedence as you would have also noticed, the bodies above bare a lot of resemblance to a planet and it's moon. Yet another point for Einstein's General Relativity

Although restraining two bodies at a distance relative to each other is quite cool. Even more fun than a simple distance constraint is a multiple distance constraint where each body is constrained to the one before and or after it, with each point of contact between the bodies acting as a sort of spine.
Using this simple concept we are able to simulate the movement of different animals, ranging from worms to reptiles.

In order to properly simulate animal movement a few faults are to be considered, for example;
The body of our animal curving in on itself and bending past what we would consider natural .
With the introduction of a few rules like;
1> Preventing every Nth circle from colliding with circle Nth+2 and Nth-2
2> Enabling the "head" to collide with the rest of the body.
We achieve a more natural movement for our animal, concluding our biological simulation.