This is useful if you link in items from another document or information repository than SharePoint. Often the links will point to Office format files or PDF’s which is all good, and they display just fine in the document library with icons.
You see the PDF icon with a small arrow overlayed. These are actually two images, one for the icon and one for the arrow.
Once you go to the search page the story is different. icons does not show as the links themselves are stored as .aspx files in the library.