The mechanical shell was largely enclosed. And on the last side where it connected with other parts, a large number of the gear structures were invisible.
Of course, being "invisible to the naked eye" was a manageable situation. With the advancement of technology, there were now numerous technologies that could peer into the internal structure of an item without damaging its exterior.
Like various kinds of rays.
If a creature's vision was based on X-ray, then in its eyes, trees would appear crystalline, and the flesh and organs of animals would be semi-transparent. It could clearly see the shadows on the organs.
Except, the material of this thing was a specially made alloy, which was difficult for most rays to penetrate.
In addition, Xiang Shan weighed it in his hand and tapped it a few times. From the tactile feedback, there seemed to be cavities and sound-absorbing materials inside designed to interfere with ultrasonic detection.