A bald-headed member of the tracking station staff walked in. He carried an object of clear plastic. It was a foot and a half long, about six inches in diameter. There was an infinite complexity of metallic parts enclosed in the plastic.
"I caught one of the fishermen making off with this," he said in a flat voice. "It was fastened to one of the squid's shorter arms. The fishermen didn't want to give it up. The skipper claimed it as treasure-trove."
He put it down on the table. Davis, Terry and Morton looked at it. Then Morton shrugged his shoulders, almost up to his ears.
"The intelligent being that made it," said Davis, "apparently came down from the sky in a bolide. That's easier to believe than that a submarine civilization of earthly origin lives down in the depths. But why would anybody prefer the bottom of the sea to—anywhere else on earth? Where would such a creature come from?"
Deirdre walked in and stood by the table, watching Terry's face. The bald-headed man said, "I could believe some pretty strange things, but you can't make me believe that a creature can develop intelligence without plenty of oxygen. There's not much free oxygen at the bottom of the sea."
"But there's something intelligent down there," said Davis doggedly. "If it has to have free oxygen, you've only raised the question of where it gets it. Maybe it brings it."
Deirdre shook her head. "Foam," she said.
The four men stared at her. Then Terry said sharply, "That's it! On the Esperance there's a picture of a huge mass of foam on the sea. A ship dropped right out of sight right into it. Deirdre found the answer! Something down below needs free oxygen. In quantity. Why not get it from the water? What to do with the hydrogen that is left? Let it loose! It'll come to the surface, make a foam-patch...."
Dr. Morton said with a sort of mirthless geniality, "I add a stroke of pure genius! Davis just asked what would be the origin of a creature which preferred the depths of the sea to any other place on earth. What's to be found down there that's missing everywhere else? Cold? No. Moisture? No. Just two things! Darkness and pressure! At the bottom of the Luzon Deep the pressure is over seven tons to the square inch. There's no light—I repeat, none—below three hundred fathoms. Down at the sea-bottom it's black, black, black! Now, where in the universe could there be creatures capable of riding down here in a bolide, and in need of an environment like that?"
Terry shook his head. He remembered seeing a book on the solar planets, in the after-cabin of the Esperance. He hadn't read it. The others on the yacht must have.