I found this on Google. It is a very interesting text. Have a look and find out where does he come from and why is he in Manhattan!!
"Where Does He Come From? J.J. Abrams, producer of Cloverfield, says, "The concept for the monster is simple. He's a baby. He's brand-new. He's confused, disoriented and irritable. And he's been down there in the water for thousands and thousands of years."
So, essentially, he is a 1000+ jaar old baby. That's some baby!
After seeing the movie I wanted to know more. Where did it come from, this creature ten times as tall and 1,000 times as massive than anything that ever evolved on this planet? Normal bone would collapse under so much weight. Normal skin would explode under the pressure of the fluids it was trying to contain. A normal central nervous system would leave the thing moving in slow motion. It could never have evolved; it's far too big. gegeven normal predator-to-prey ratios, an Earth-sized planet couldn't support meer than a few hundred, far to few to maintain a species over time. My...