BLUE TOUNGE SKINK

Question
I've had Ernesto, my Northern Blue-Tongue, for over a year. I often let him in my front yard to do some exploring. I've noticed that he eats small rocks. I've tried stopping him and he hisses at me. This is the only time that he ever gets defensive. I'm just wondering if this is normal or if he's missing something from his diet.

Answer
Hmmm, I'm stumped.  I know birds eat small rocks to use to grind their food in their gizzard but as far as I know all reptiles have a stomach just like ours.  Maybe he thinks they are little eggs???  Sorry, I can't be of more help.  Do they come out the other end ok?  That would be what I would worry about.