Example of questionable manifold object

manifold.stl

solid OpenSCAD_Model
  facet normal 0 0 0
    outer loop
vertex -10 0 10
vertex 0 -10 10
vertex 0 0 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 0 10
vertex -10 -10 10
vertex 0 -10 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 -10 0
vertex -10 0 0
vertex 0 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 -10 0
vertex -10 -10 0
vertex -10 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 -10 10
vertex 0 -10 0
vertex 0 -10 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 -10 10
vertex -10 -10 0
vertex 0 -10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 -10 10
vertex 0 0 0
vertex 0 0 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 -10 10
vertex 0 -10 0
vertex 0 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 0 10
vertex 0 0 0
vertex -10 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 0 10
vertex 0 0 10
vertex 0 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 -10 10
vertex -10 0 0
vertex -10 -10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex -10 -10 10
vertex -10 0 10
vertex -10 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 10 10
vertex 10 0 10
vertex 10 10 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 10 10
vertex 0 0 10
vertex 10 0 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 10 0 0
vertex 0 10 0
vertex 10 10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 10 0 0
vertex 0 0 0
vertex 0 10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 0 10
vertex 10 0 0
vertex 10 0 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 0 10
vertex 0 0 0
vertex 10 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 10 0 10
vertex 10 10 0
vertex 10 10 10
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 10 0 10
vertex 10 0 0
vertex 10 10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 10 10
vertex 10 10 0
vertex 0 10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 10 10
vertex 10 10 10
vertex 10 10 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 0 10
vertex 0 10 0
vertex 0 0 0
    endloop
  endfacet
  facet normal 0 0 0
    outer loop
vertex 0 0 10
vertex 0 10 10
vertex 0 10 0
    endloop
  endfacet
endsolid OpenSCAD_Model