I saw a picture of such a model in an exhibition book that featured Tomoko Fuse's work. You cut two sides of an isosceles triangle, and then use the flap to fold a spiral. Depending on the angles you choose while folding the spiral, the result will take different shapes. I decided to try my best to fold the angles evenly, thus resulting in a spiral that lies central on the third side of the triangle.
Paper: 19.5cm square of transparent paper