Re: growing solely due to energy collection?
No, this one was worse than Treknology. Treknology at least makes an attempt at explaining what was happening. This one made none at all.
Oh, and according to the episode there are no minerals on the moon. None at all. It's just a shell. With antibodies that look EXACTLY like giant spiders.
And for the record, I am getting quite tired of the sonic screwdriver being the equivalent of Harry Potter's wand. All of the Doctors up to the new series used other gizmos besides the sonic. In fact, when the sonic was first introduced, it was exactly what it's name implied a fancy screwdriver that didn't care about the head type on the screw. We could do with a bit more of that in the current series.