"Far from it," Bergdorf replied. "I said oysters and I mean oysters. It's no joke! Just who was the unutterable idiot who planted them here?" It took a minute before I remembered. "Hartmann," I said. "Of the BIT. He ordered them delivered at the request of Kron Avar and Tovan Harl. I suppose Harl planted them. I never paid very much attention to it." "You should have. It would have been better if they had imported Bengal tigers! How long ago did this infernal insanity happen?" "Right after the Agreement was signed, I guess. I'm sure it was no earlier than that, because Niobians met up with oysters for the first time at that affair." I still didn't get it, but there was no doubt that Heinz was serious. I tried to remember something about oysters, but other than the fact that they were good to eat and produced pearls I could think of nothing. Yet Bergdorf looked like the end of the world was at hand. There was something here that didn't add up. "Well, get on with it," I said. "As far as marine biology is concerned I'm as innocent as a Lyranian virgin. Tell me--what's wrong with the oysters?" "Nothing! That's the trouble. They're nice healthy specimens of terrestrial _Ostrea lurida_. We found a floating limb with about a dozen spat clinging to it." "Spat?" "Immature oysters." "Oh. Is that bad?" "Sure it's bad. I suppose I'd better explain," Bergdorf said. "On Earth an oyster wouldn't be anything to worry about, even though it produces somewhere between sixteen and sixty million fertile eggs every year. On Earth this tremendous fertility is necessary for survival, but here on Niobe where there are no natural enemies to speak of, it's absolutely deadly! "Just take these dozen spat we found. Year after next, they'd be breeding size, and would produce about three hundred million larvae. If everything went right, some three years later those three hundred million would produce _nine thousand trillion_ baby oysters! Can you image how much territory nine thousand trillion oysters would cover?" I stopped listening right then, and started looking at the map of Niobe pinned on the wall. "Good Lord! They'd cover the whole eastern seaboard of Alpha from pole to pole." Bergdorf said smugly, "Actually, you're a bit over on your guess. Considering the short free swimming stage of the larvae, the slow eastern seaboard currents, poor bottom conditions and overcrowding, I doubt if they would cover more than a thousand miles of coastline by the fourth year. Most of them would die from environmental pressures. "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.