Greg Cox wrote:
I went another way in the new book. I decided that the exploding rocks were an accidental byproduct of the terraforming process that maintained idyllic, garden-like conditions across the entire planet, and that poison plants were not poisonous to the Vaalians, but only to intruders.
And, yeah, I assumed the Vaalians were "feeding" Vaal with fruits, vegetables, and other organic matter . . . .which I rationalized as being a sustainable energy source that could be safely provided by even a primitive people without any technological skills.
Hmm... on the one hand, those screencaps do show them feeding Vaal rocks, so we seem to have been wrong all these years to think it was food -- but on the other hand, the idea that they're feeding it rocks doesn't make a lot of sense. Are these rocks just lying around all over the place? Wouldn't they be depleted eventually if people are constantly gathering them and feeding them into Vaal's mouth? You make a good point that the fuel source would need to be sustainable indefinitely, and a mineral fuel would not be sustainable for long unless the natives engaged in mining, which clearly they don't.
So maybe this is a case where we have to ignore the "right" answer as implausible and stick to our old "wrong" assumption because it actually makes more sense.