I keep an adult male Russian, named Steve. He is a pretty active, aggressive individual, especially on warmer, sunnier days, as expected. He is often quite intimate with a particular rock in his enclosure, the frequency of which I can only assume is typical. He usually bites the rock beforehand, and sometimes I'm worried about how hard he's biting. Steve used to have a longer beak, but years ago, we were able to trim it with nail clippers and then file it down a bit more. Eating seems to be easier for him now that his beak is shorter. I'm wondering: is it too worn down now? Is there a risk that his beak might crack? Should I supplement his diet with extra calcium? Is the rock a concern and should I remove it for a little while?