[mike31154]

Yoiks, a masonry bit should take care of most any rock like material! Have you tried or do you have access to, dare I say it, a hammer drill to use with the masonry bit? The hammering action can make quite a difference, although it might just shatter the rock too. I know some of my pieces are rather fragile and I've broken several just rearranging them in the tank. The stuff you're dealing with sounds bulletproof though.

Didn't you mention finding some fishing line on some of the stuff? That made me think, could it be that a previous owner of the rock used that to hold it together in some fashion? Anyhow, good luck with that, usally the next day, previous frustrations are forgotten and things tend to work better. You certainly have the build well planned with regard to where you're going and what livestock...