It's an implementation of John Conway's classic zero-player game, "Game of life" on a 3D grid, which is populated automatically.

The final version has a life-cycle and a growth stage added. Cells now age, are able to die of old-age, and their age affects reproduction and chance to die of lonelyness. The "Growth" stage occurs when a cell that doesn't suffer from eliminating factors has enough room to expand. Big cells follow the same rules as regular cells.

The downloadable blend-files contain the final work, as well as a version, featuring vanilla game of life rules.