I read it similarly - as the present article for this post says, these were carved of “living rock”, which I take to mean that rock/dirt was removed from around

I read it similarly - as the present article for this post says, these were carved of “living rock”, which I take to mean that rock/dirt was removed from around the megalithic sculptures. In this context, the refill was when these hollowed out areas were covered back up. I read “uselife” similarly to you - the end of their usability vis a vis the refill.