Mammoth-Killing Pentagon

Here's the letter I wrote back to the pentagon in response to his first letter:

Dear Pentagon,
You should at least try to come back. I imagine it's cold in the Ice Age, and you didn't take any sweaters with you or anything. Even if you didn't make it back to the present, you'd probably end up somewhere where they can give you a blanket. Also, I'm pretty sure you're not immortal, and even if you were, it's best not to put that to the test.

Sincerely,
Ben

And then, like right after I sent it, I got another response with this picture:


Dear Ben,
Thanks for your letter, though I am not quite sure how I received it. I appreciated your sentiment about the weather. As you can see from the picture, I made myself a robe of mammoth fur.

Which leads to my main reason for writing: I've joined a tribe of nomadic cavemen and have developed a taste for mammoth hunting. I believe that this is my calling, and I plan to stay here in this time to teach and aid my caveman brethren.

We will probably never see each other again. It would be best for you not to write, I think. We should just move on with our lives.

Sincerely,
Infinity Pentagon

Oh well. At least he won't freeze to death now.