The aliens arrived in a spaceship filled with water. Recognizing a habitable environment, they landed in the middle of the ocean. Their ship transformed, and they sank beneath the surface. They sampled the water and found primitive life forms but no sign of higher technology. They pulsed messages out into the deep, but the only replies were distorted echoes. After a time, they changed the ship again and launched back into space. Despite the promise of so much water, the planet had no intelligent life.