Cdonald shape

Figure 1

cDonald's Theorem is described by the following equation:

n² + 9 + 9

If we plot its graph, the result is a uniformly curved line that somehow joins up with itself (as shown in figure one), a shape for which science is yet to find a name!

Can you think of a name for it? If you can, the Royal Mathematics Society would like to hear from you. Because they hold a competition each year to find a name for this figure. The final takes place in Nottingham on April the 4th of September. And you could win your school a computerised toast system