Spiral

This is a simple spiral. All that has been done is rotate a shape - square in this case - by 1 degree while continually reducing its size.

startshape FIGURE
background{b -1}
rule FIGURE {
SHAPES{}
}

rule SHAPES {
SHAPE{}
SHAPES{s -0.99 r 1}
}

rule SHAPE {
SQUARE{}
SQUARE{s 0.99 hue 30 sat 1 b 1}
}