It's a rather rare curve to find in math. Its form is a bit alike a hyperbola, but it is not one. And it is a sextic curve, with Cartesian equation:
x^{2} (3x^{2}-y^{2})^{2 }= y^{2 }(x^{2}+y^{2})
The curve can be extended to the generalized arcs of Samothrace.