The spring in a
clockwork toy, clock or watch is in the shape of a spiral. Spirals
are to be found in nature in the arrangement of seeds in a sunflower
head.
A three-dimensional spiral (known as a helix) can be seen as
the thread on a screw, the path of a spiral staircase in a lighthouse,
or in nature on a sea shell or as the pattern of seeds on a fir cone.
A spiral can be drawn by winding a piece of string around a pencil,
attaching the free end to a drawing pin in the center of a piece of
paper and then drawing round and round with the string taut, letting
it unwind.
