Split/Divide and Multiply:
I'm trying to think of anything, cells, atoms, (obviously I'm new to this field - science) etc. that can "split in half" or "be divided" (physically), however rebuild / multiply afterwards.
Ideas, specifics welcome. I'm sitting here bored and thought I'd try to get some productive thinking (or imagination) going. :P
An example that doesn't fit realistic terms (I'm shooting for realistic over unrealistic) is a Ditto from red version, being cut in half, then there being 2 ditto's, of the same size. (pokemon - don't think this ever happened, just trying to convey an image / idea of what I was thinking)