Isaac: May I ask why you terminated your coupling?
Bortus: We were incompatible.
Gordon: When Moclans break up, is there, like, all that stabbing, like with the divorce?
Bortus: No. Each Moclan extracts a tooth and leaves it with his former mate.
Gordon: Yeah. I knew it had to be something like that.
Ed: Do you still have the tooth?
Bortus: No. It is given to the next mate.
Gordon: Uh, let me guess. He eats it.
Bortus: That is correct.
Gordon: Yes! Man, I'm getting so good at this.
Officer Alara Kitan: Captain, there's a message coming in from Admiral Halsey. It says that an executive officer has become available and can rendezvous with the Orville at station 794.
Captain Ed Mercer: That's great. That's barely out of our way. Who is it?
Officer Kitan: He wants me to forward it to you privately.
Captain Mercer: Alright, send it to my station. [Reads message.] No. No, no, no, no.
Lieutenant Gordon Malloy: What's the matter?
Captain Mercer: [Running out of room] No, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no.
Answer: The book "Flatland", which is mentioned in the show, is a real book that may answer your questions in full (it's the story of a 3-D being experiencing the 2-D world and the 1-D world). In the 2-D world, there is no height, so there's no way to slice anything in half (horizontally). A being living in the 2-D world sees any object or being as a line (it's messy, but the lines have thickness, just not height, but all thickness is the same). So if the Orville was seen, it would only be seen 2 dimensionally and be seen as a line and others beings could just move out of the way. While there were buildings in "Flatland", perhaps this world doesn't have any, or the Orville didn't bump into any. There is death in "Flatland" when a being isn't careful and is poked, but these are usually by lines and triangles and the Orville would more like the circles and not in danger of poking anything.
Bishop73