Neon Microcosm Lite

This live wallpaper and daydream simulates a swim through a 3D colony of glowing microbes. Neon Microcosm is descended from the original Microcosm, and features a more intense color scheme and depth-of-field effects.

The full version lets you tap the screen to spawn new cells. It also includes several more color themes, and the option to select any colors you like to create your own custom theme.