Maybe the sand plankton performs some form of photosynthesis.
Hmm, didn’t know that. In The Kaiju Preservation Society by John Scalzi, the Godzilla-like monsters in question are described as being their own unique, mobile ecologies powered by self-contained organic nuclear reactors. Weird, farfetched but intriguing.
It’s an interesting topic: how much science is really used and correct in various SF books?
Mission of Gravity by Hal Clement, for example?
But probably a bit of a diversion here. I think a new thread might be in order…