Radiolarians was originally an orchestral piece and my masters thesis. Having never heard the orchestral version, I made a piano transcription a few years ago and decided that it worked better as a solo piano piece. I could write stuff about how it is constructed, but I find that when composers do that, it's really boring. Also, if the piece needs a theoretical justification to exist, it's probably not worth the listen. Such issues should only be of interest to composers and theorists. Radiolarians themselves are pretty cool things and quite beautiful. Google them!