Ok so first off the tank is a 29 gal running for 5-6 months. Rest of tank info at signature. So all the LR i got was from the same store. Bought same time.
After about 2-3 weeks or getting the tank running I noticed to holes in the side of my biggest and nicest piece . The holes looked like some one took a drill and made two holes side by side about the size of a dime. Their is about 2 mm in between the two holes. So I put my hand in to investigate and right when I touched the part in between it fell to dust. The hole area around it just started to fall apart and go deeper into the rock. It went in farther then i wanted to stick my finger

. So I left it and thought maybe it was the sand that did not settle when i switched from crushed coral to LS.
Fastforward to know. I have since noticed more holes in my rock and it appears that it is moving or their are more then one. 4 rocks over more holes the same size . Also during normal weekly water change and tank up keep I picked up the rock that originally had the problem and when I did sand just started to poor out of the rock from the bottom out of a hole. I know its not the sand from the bed as this sand is like dust and always has a much darker tinge.
First off I know its not a mantis as the tank has been up 5-6 months and never once have herd any clicking sound. Its not a rock urchin as I since have added one and he just skims the top of the rock. Plus the holes are way to deep and it was their before him. I am getting two the point were I am dosing and want to add my corals but I am scared as If this thing eats rock like that it will prob make short work of them.
I have no idea what it is but i know its not that big as I always look into the tank when lights are out and never see anything out of the normal.
I cant afford to go out and just buy 40 more lbs of LR. Plus I dont trust that place for good LR any more (BigAls Young&Steels) . Their is live stock know in the tank and I dont want to recycle with new LR as their is no were to get rock that is 100& cycled that I know of other then waiting on a used tank. Also My rock has alot of iso,cope,and amphipods . I kinda dont wanna get rid of them but what do I do? any ideas or help at what this could be or what to do would be a great great help.I would re cure the rock piece by piece but how do I know its just not moving from them when I do that.
Thanks again Everyone.