Space-time square spiral, made with Open SCAD, dervide from a simle LibreLogo script:
TO SPIRAL IL EL DS A
IF IL < EL [ STOP ]
FORWARD IL
LEFT A
SPIRAL IL–DS EL DS A
END
SPIRAL 50 5 0.5 89
where
IL: initial lenght
EL: ending leght
DS: decreasing step
A: turning angle