Apart from that, this method of rendering the cells makes it appear like you have more cytoplasm than you actually do, it's a bit misleading.
I always thought it'd be neat if (when this is implemented) cells start off as amorphous blobs. And they stay amorphous blobs until you evolve the membrane to have a pellicle. A pellicle is a stiff but elastic membrane that gives single celled organisms (like the paramecium or my personal favorite, Lacrymaria olor) ttheir distinctive shape, while at the same time allowing for small changes such as stretching and squeezing.
Edit: A further membrane upgrade would be a fustule like diatoms, or the cell wall (already planned).