The Scrap Fan is an unused piece of something found in Metal Slug 7. The only thing found in the game's tiles are this spinning animation and the thing destroyed, which makes it hard to guess what exactly this is. Apparently, it was supposed to be part of a larger vehicle. Some people theorized this would be part of an underwater vehicle like a submarine, but since there is no data on the game of an underwater level, this is very unlikely. A more likely answer would be that it was originally going to a piece of the Worm Mecha (As seen from the metal wrappings around it.) In addition, it could also be a piece from the tentacles of Kraken.