Atlas was too big to pop when I got him and I don't know anyone who probes. S/He is healthy, growing, eating, shedding, so no need for a vet visit just to determine sex. I got my corn, King Crimson before I knew better, and by the time I did s/he was also too big to pop. KC was sold to me as male, but I have my doubts about the validity of that claim. Like I said, it doesn't really matter since I have no plans to breed.