I believe that he had been shrunken with all his fluids removed to preserve him for his long, long trip to Earth. See, he is less than four inches tall:
He was in this envelope and it didn't have a return address or a stamp on it. You may want to click on the picture to enlarge it so you can read it easier.
After a couple of hours, he had grown to seven inches tall and got a lot fatter.
And view from the front:
I guess the pups, my wife, and I will try to give him a good home until he can figure out how to get back to his home. Now, you all have a great day, you hear?