it's actually not a heat rock, sorry it's a clay rock with a cave it was used when i had my beardie. the tank i am using is also the tank i had built for a mangrove monitor that passed away in June unknown reason why. it was fine sat and sun it was lifeless. I know I need another 1 or 2 hiding rocks/logs for him but i never thought the tank was too big. I figured he'd want room to move and not be cramped