Seashell Surface - Parametrization

Parametrization

The following is a parameterization of one seashell surface:

$\begin{align} x & {} = \frac{5}{4}\left(1-\frac{v}{2\pi}\right)\cos(2v)(1+\cos u)+\cos 2v \\ \\ y & {} = \frac{5}{4}\left(1-\frac{v}{2\pi}\right)\sin(2v)(1+\cos u)+\sin 2v \\ \\ z & {} = \frac{10v}{2\pi}+\frac{5}{4}\left(1-\frac{v}{2\pi}\right)\sin(u)+15 \end{align}$