Scientists have discovered the fossil of what seems to be a dolphin with a "balloon head", well they're not actually dolphins, they are aliens!
This particular type of "alien dolphin" was let loose by an alien warship 2 million years ago passing by planet earth thinking "this planet could do with some intelligent beings!"
They knew that their "balloonheaded" dolphins were really very intelligent, so they hovered over the North Sea and dropped several of their "balloonheaded" dolphins, male and female in, clever!
The "balloonheaded" dolphins found are actually fossils of dolphins wearing space helmets. They bred very successfully in the earths pristine waters, evolved and became the most intelligent being on the planet until mankind, thick as two bricks, started to hunt them, eat them and lock them up in Sea world.
After a couple of million years the "balloonheaded" dolphins evolved leaving their helmets behind them and although were hunted by their human, less intelligent counterparts, they have managed to survive and continue to provide evidence that they are much more intelligent than humans.
Recent sitings of alien spaceships over Rotherham, UK, only go to prove that aliens do visit our planet, want nothing to do with the ignorant human race, but still love to watch their dolphins swimming happily in the now humanely polluted North Sea trying to avoid the stupid humans attempting to catch a fish or two.
Maybe humans should ask the dolphins how to do it properly, fishing I mean!