After looking into and considering all four life cycles, the Slime Mold is definitely the one I was most drawn to after further research into the stages of it. I have looked at multiple diagrams which show the key stages in its life cycle, the ones below are diagrams that I found particularly interesting or useful in breaking the cycle down.
One another note, apparently my old buddy and 'What If Metropolis' work colleague Ernst Haeckel has created a print specifically of Slime Mold. This could be a good source for some inspiration.
While my ideas are only starting to flow for this project, one thing I would like to consider is narrating from the perspective of the slime mold itself. It is something I haven't seen in the previous animations and it could make the animation I make more interesting. It is of course not certain yet but it is something to think about as I move forwards.