“Jiang, what has you so excited? It’s really urgent?”

“Just watch the video, all I ask, Ranveer.”

“Ok, somebody on the Great Wall of China, walking funny, big deal?”

“Our recognition engine gait-matches this video from Badaling to what you gave us from Roosevelt Island.”

“Oh! They came to China too?”

“Probably when they checked out our ‘uranium.’ But that’s not what I wanted to show you. Their illusion only covered visible light; look at the terahertz and infrared images! You see their real shape!”

“Those legs — if they are legs, look all wrong. How do they move like that?”

“Wuzhou studied it. The muscles, I guess we can call them that, are only on the inside of the joints. Nothing bulges on the outside. So when they bend the joint, the muscles contract and the adduction looks normal. But there is nothing to contract on the outside. The muscles on the inside don’t just pull, they push. To extend a joint, they push from the inside!”

“That means . . .”

“The forces are entirely different. The skeleton has different stresses. Their . . .bones, I guess . . . are under more tensile stress, not just compressive stress, which means their chemistry probably isn’t mostly calcium. Evolution here uses calcium over and over, but there it doesn’t. So the likely explanation is that calcium isn’t as common there as it is here.”

“Okay . . . So the relative composition of minerals on their planet is different. They came so far to get uranium because they didn’t have enough there, we thought, but this confirms it. The elemental physics of their planet’s formation differs from ours.”

“Yes, and to think that we can infer something about xenogeology from the motion of the limbs of a creature! Adduction looks normal, but . . .”

“Absolutely! Alien abduction.”