I do have my base live rock directly on the ground, I was more worried about the upper tiers falling. The "tunneling" appears to have slowed down a bit. I think it might be some of my hermit crabs because I have discovered them poking around near the newly formed holes.
You can see some of the holes I'm talking about above. There is some sort of feather duster worm thingy in one of the holes, but hermit crabs are hanging out near the other holes like right here: