Take any random point in the plane with a spiral drawn on.
It is obvious that the chances that this point is part of the spiral (the solution) is very very small.
Imagine an empty plane, with a centre point. Now pick a random point on that plane.
The amount of spirals starting in that centre and and go trough that random point is like endless.
At the same time, if the spiral has to be eye appealing and constructible with a limited amount of objects, then the solution will mostly be 1 rotated or scaled spiral. The demand of an eye appealing spiral constrains the problem to the very first question, which i started this text with.
So, lets be lazy, to start with.
In stead of searching for a missing spiral, lets draw that special spiral that we like and love. And build it from out to inside.
https://www.dropbox.com/s/7cly93r7zl3b8 ... .capx?dl=0
Set the placeholders invisible in the end product.