You know... do you think Nareko developed into this form because of the pyramid? Going by the Three Fairies manga, a jizō statue would remain a statue if it's not given faith through being by the roadside. So perhaps something inside the pyramid, the altar I suppose, was the one that animated her, just like how Narumi came to life from the Forest of Magic?
Or was Nareko already developed before being placed to watch over the pyramid? 🤔