Not to mention that Rush is just using the word "shrimp" out of simplicity. All we know about them for sure is that they may look shrimp-like, they emit harmful light, and they are telepathic. When their existence is proven, and it will be, do not be surprised if they do not align with your preconceptions.
I'm sure that if Rush weren't delusional or lying, that he could draw what he's seen, have skeptics view through his magic telescope, and about a dozen other definitive efforts. Of course that he hasn't done so means that he's delusional or lying.
As we know, the shrimp-like creatures ARE telepathic. They choose who to reveal themselves to and who not to. I once talked to a Native American who said that he used to conduct sweat lodges and in the glowing red stones he would often see what he thought looked like shrimp. He didn't know why, but for years after that, he was inexplicably drawn to the magnificence of the moon. Innately though, he knew not to stare at it for long periods. Eventually, he bought a telascope and gazed at the moon. That night, having finally gone the extra mile, the moon creatures showed themselves to my friend. He had many questions for them that they were more than willing to answer. They told him that most people only see shaded craters when they look at the moon because that's what the creatures want them to see. They also warned mankind to be more respectful of their environment and when my friend asked why they appeared to him, they told him it was because he was special and open minded.
Now, I know that the creatures telepathically show themselves to Earthlings, it's happened to at least one person on this forum. I dont know if they actually look like shrimp or if that's how they choose to be seen. Now, if Rush had a similar experience, I cannot say. Perhaps they are waiting for him to take just one more step.