Spirangle

3-angle spirangle or triangle spiral
Ulam spiral in a 4-angle spirangle or rectangle spiral
7-angle spirangle or heptagon spiral
70-angle spirangle

In geometry, a spirangle is a spiral polygonal chain. Spirangles are similar to spirals in that they expand from a center point as they grow larger, but they are made out of straight line segments, instead of curves. Spirangle vectographs are used in vision therapy to promote stereopsis and help resolve problems with hand–eye coordination.