Caligulaaaaa..... where are you?

Recently I have noticed that I not seen Caligula, (newest member of the tank) I know he's nocturnal and shy, but yesterday (his FIRST day) he would come out on occasion. I have not seen him ALL day! Out of curiousity, I lifted up the artificial coral that he usually hides under, but he was nowhere in sight. This worries me. I've checked everywhere! I hope to find him soon..... maybe Zeus ate him!