The name of the curve is <A HREF="https://en.wikipedia.org/wiki/Cochleoid">cochleoid</A> (= shell-shaped rather than *cardioid* = heart-shaped).

I compare the two below (gold = cochleoid, blue = cardioid). The distinction shell/heart refers to the additional windings remarked upon by მამუკა ჯიბლაძე , without these windings the two shapes would be qualitatively the same.

<IMG SRC="https://ilorentz.org/beenakker/MO/cardioid_cochleoid.png" WIDTH="300"/>