This is 3D desinger shell for a hermit crab. The thickness of the shell is 1mm to accomodate the use of transparent acrylic. The parametric equations to produce this particular variation of the 3D parametric shell are:
x(u,v) = 1.2^v*(sin(u)^10*sin(v))
y(u,v) = 1.2^v*(sin(u)^2*cos(v))
z(u,v) = 1.2^v*(sin(u-.4)*cos(u+.4))
It is possible to create this shape and export to stl or obj format using mathmod, a 3D surface modeling open source software. This particular model was produced using the R statistical programming language, and the script to produce it can be found in this Linkedin article.
More details, and instructions on how to make this by yourself can be found in this Linkedin Article: Parametric 3D Shell using R.