Drilling into reef bones

[DanG]

I bought 2 big chunks of reef bones yesterday and have decided I want to make come caves and holes in them for my fish before I cycle them.
I will use a masonary bit for the smaller holes, but I also have a 3 inch metal hole saw. Would that be able to punch through the reef bones? They're fairly porus, so I think it should work.

Any advice?