While attempting to resolve what to do for the look of the sporozoite I had an alternative idea for the gamete cells combining: Instead of the male slotting into the female, they could instead twist around each other and begin merging as the ookynate/zygote shell begins surrounding them.
The main argument was that the sporozoite looked too different, too disparately organic from the more pellet-like merozoites and gametes. But I also want to keep a machine feel to it.
This was a rather hasty attempt to create the below material which I feel is both Gigeresque and as a form of industrial tubing it adds a machine-feel to the objects that it covers. So it could be a way to explain the flexibility of the sporozoites and gameetes without making them look too organic compared to the merozoites.