question:  What didn't surprise Casey about Jupiter?
context: JUPITER'S JOKE By A. L. HALEY Casey Ritter, the guy who never turned down a dare, breathed a prayer to the gods of idiots and spacemen, and headed in toward the great red spot of terrible Jupiter. Sure, the crystals are deadly, but I was smuggling them legitimately, in a manner of speaking, for this doctor to experiment with. But—and this was the 'but' that was likely to deprive the System of my activities—even experimenting with them was illegal even if it needed to be done; also, I had promised not to rat on him before taking the job. And instead, blast me, if they didn't foul me with this trip to good old Jupiter. Jupiter was worse than the pen, a lot worse. Jupiter was a death sentence. "You've no doubt heard tales of the strange population of Jupiter," he said. How could any—" The senior judge rapped ferociously, and I skidded to a halt. We possess well-authenticated photographs of these inhabitants, and if you are prepared to visit them and in some way worm from them the secret of their anti-gravity field, the government stands ready to issue you a full pardon as well as a substantial monetary reward. That whole Kooleen caper: Had it been just a trap to lead me straight to this? Well, a cross between a scorpion and a grasshopper, to be accurate. "I just made a pass at the Killicut Emeralds, that's all, and got nabbed." "What were you trying to do, start a feud between us and Mars?" Those emeralds were in the inner shrine of the super-sacred, super-secret temple of the cavern-dwelling tribe of Killicuts on Mars—the real aborigines. My jaw must've been hanging down a foot, because I'd just been playing along with him, not really believing him, and now all of a sudden I somehow knew that he'd really lifted those emeralds.
output:  the aliens communicated by tapping
options:  the red coloring was plants  items could float in mid-air  the aliens could remove their eyeballs  the aliens communicated by tapping