I began to say something there but he held up a hand to stop me. "Possibly an exploring spaceship from the alien planet was looking for colony sites. When it got to our solar system it left some of these animals with the idea of coming back in a few thousand years or so to see if the zloors were able to adapt themselves to the conditions existing here." I ran my tongue over suddenly dry lips. "You mean that if the zloors can live in our solar system, then these more intelligent aliens would figure they could use our sun system for a colonizing project?" He nodded. "Holy Wodo," I said. "No wonder they want some specimens to work on back on Earth." He relaxed again. "Well, at the rate we're going, it'll be a long time before earth laboratories ever have the opportunity to mess around with our pal the zloor." * * * * * I got a chair and sat down facing him and said seriously, "Mike, brief me on what you and the other fellows have tried." "You don't have to ask. That goes with membership in the club," he grinned. "Among other things, we've tried building a steel box around one of them with the idea of putting wheels on it later." "That sounds good." "Uh huh. The trouble was that when the zloor felt like moving he walked right through the side of the steel box like you or I'd walk through a wall of tissue paper." "How about poisoning one?" I rapped. "You could get a dead one back a lot easier than--" "They don't poison," he said, "and from what we can figure they're practically immortal. We have never found a dead one." "What'd'ya mean, they don't poison?" "Just that. Nap, that animal can eat _anything_ organic and thrive on it. Evidently, no poison that nature has ever produced affects it. At least, none of us have been able to dream one up." "How about narcotics, something to dope it?" He shook his head. "To begin with, some of these Martian plants produce narcotic effects that make the products of our poppy look like food for babes; but the zloor takes them in its stride. It's _really_ got a cast iron stomach. We've never been able to locate anything it won't eat and enjoy eating." I didn't say anything for a long time. Then, "A Bazook-rifle would kill one." "Sure," he said, "and splatter it all around the scenery at the same time. The laboratories need a _good_ specimen." There was another long silence. Finally I said, "Why in the name of Wodo don't they sink into the ground if they weigh as much as all that?" "They would, only they make a point of walking on rock. That must be one of the things that limits their spreading even more widely. They have to be able to forage on ground that supports very little vegetation." "You could lift one with a derrick."