Figi Live Rock

[pezlok]

I have noticed several cylinder like holes in my live rock. The cylinder cores are laying on the bottom of my tank. What causes this?

 

[burnnspy]

Different types of borring worms, pistol shrimps and mantis shrimps can do that. I bet its a worm though.
BurnNSpy

 

[hermit enthusiast]

I would think that it's a worm to because if it was a mantis shrimp you would have found him and if it was a pistol shrimp you would have heard him. Hope it is a worm.