The circle reminds me of consistent hashing. The most popular method is to make a circle and place nodes at different points along the circumference.

A circle is an elegant way to encapsulate a lot of information in a compact symbol. These aliens could be really good at detecting angles. If their eyes have cones polarized at different angles, shapes placed at different points on the circle could appear to be written in different colors to them. That would be just as natural as words written in a line are to us. Fascinating stuff.