I think the idea of radially symmetric alien organisms is really exciting in the questions it raises about function and design.
For those who don't know, humans are bilaterally symmetrical. If you slice down the middle of a human, you get 2 symmetrical halves. So if half a human has one eye, one ear, one arm, one leg and one brain lobe then both halves together have two of each thing. Blatantly obvious, but bear with me.
I'm designing a "human" that's tetramerically symmetrical. That's an animal made up of 4 symmetric slices. Therefor my radial human would have 4 of each thing total because there are 4 slices.
Not a hundred percent finalized on this design, but each slice of the face would have a large eye in the middle, so it would have 360 degree vision. I may have to cheat and have two nostrils in each slice, since just having one right below the eye may make pinpointing smell harder.
Not quite sure on the ears yet, that'll be another question along with how the mouth would work. There would be 4 arms and legs total, likely with a ball and socket joint in the wrists for improved manipulation.
This thing is freaky as all get out, But I've been struck with a question. There are 4 brain lobes, but this brain obviously wouldn't just be two human brains stuck together. They need to be placed in a way that optimizes communication between all four lobes.
How would this tetramerically symmetrical brain need to be shaped/laid out to function properly?