I have been trying to clean up my model and I have found these strange lines at the border. They don't stretch all the way around the model, as to represent the border, there are only a few of them. They seem like very thin extra polygons but I can't easily delete them. When I select their verticies in Vertex/Face mode and press delete nothing happens. I have tried selecting them as edges, as faces, vertecies, but I have only been able to remove one of them. Does any one know what these are, how to remove them, and where they came from?

I first started my model with nurbs, then converted to polys to join the different parts, now I am cleaning up my geometry getting it ready to duplicate, merge, and smooth. Thanks for any help.