MathMod

MathMod allows to plot 3D mathematical surfaces, described by implicit or parametric equations, and offers a very large database of model samples that can be generated with it.
Apart from visualizing the actual shape, you are also free to edit the scripts and equations in order to understand how each parameter influences and reshapes the model.
Moreover, MathMod can also be used to export to OBJ format and generate animations that showcase how the model morphs as it is given new parameters to work with.