If I were in this sigtuation I would defenitly use the claim that aleans are not real in my essay. One example I would use would be to ask him(her) how many natural strange rock formations are their on earth. The only possibal answer would be more than he or her could count. That simpley prooves my point evan more.

One other thing that I would say would be "if aliens made it... why dont they come back to take care of it. If you study earths history you would find that most if not all ancient or religious artifact is protected. If this happened on earth and supposed we do think aliens are real and sufisticsted then why wouldent they go by the same practice. The third point that I would make would be if, they could create a rock form of that size would suggest thst they are revolutionized and would have large civilazations. Yet we have found no proof of any alien cicies or districts.

so in conclusion I would all in all say that my pionts are more than convincing and that he should be the wiser by now. And if he isnt... Too bad for him.