The issue is visible on the file
https://commons.wikimedia.org/wiki/File:Surface_d%27Enneper.stl
which is made of triangles. These triangles only appear when looked at from one of their side. This makes the 3d model not vey useful.
The result should look like other pictures in
https://commons.wikimedia.org/wiki/Category:Enneper_surface
This may be solved by having some kind of "two-sided" switch turned-on in the 3D viewer, if it exists.