Deleting Diagonals from a mesh automatically? I downloaded a low-poly gun model ".obj" online. When Imported, I discovered that the author has added weird diagonals on each face of the mesh.



I can remove them one-by-one but it will take whole day to do!

Is there any modifier to solve this?
You might be looking for limited dissolve! All you have to do is select your mesh in edit mode and search for it in the space search bar. 

Before:


After: