“””””” I did some tests but the 3dm files saved with Moi3D surfaces are not imported while those saved with RhinoV5 are imported correctly,and wonder why?”””””

Rhino uses a concept of saving the “display render mesh”

They arent using NURBS. It is basically a polygon model

MoI does not save this mesh data in a 3dm.

You should be able to get the same results if you do a “save small” in rhino. This drops out the render mesh to save on file sizes.