"But that isn't the real trouble. Niobe's oceans aren't like Earth's. They're shallow. It's a rare spot that's over forty fathoms deep. As a result, oysters can grow almost anywhere. And that's what'll happen if they aren't stopped. Inside of two decades they'll destroy this world!"
"You're being an alarmist," I said.
"Not so much as you might think. I don't suppose that the oysters will invade dry land and chase the natives from one rain puddle to another, but they'll grow without check, build oyster reefs that'll menace navigation, change the chemical composition of Niobe's oceans, pollute the water with organic debris of their rotting bodies, and so change the ecological environment of this world that only the hardiest and most adaptable life forms will be able to survive this!"
"But they'll be self-limiting," I protested.
"Sure. But by the time they limit themselves, they will eliminate about everything else."
"If you're right, then, there's only one thing to do. We'll have to let the natives know what the score is and start taking steps to get rid of them."
"Oh, I'm right. I don't think you'll find anyone who'll disagree with me. We kicked this around at the Lab for quite a spell before I came up here with it."
"Then you've undoubtedly thought of some way to get rid of them."
"Of course. That was one of the first things we did. The answer's obvious."
"Not to me."