Green Pipe
From Wild World Wiki
The Green Pipe is a gift item from Nintendo. It was sent out to players on the WFC on the 14th to 16th of April 2006. It is a piece of furniture for your house resembling the Warp Pipe containing a Pirahna Plant from the old Super Mario Bros games. It is quite a large piece of furniture at 2 squares by 2 squares, and tall enough for your character to almost hide behind.
Tom Nook will offer you 256 bells for your Green Pipe. However, note that it cannot be re-bought from the catalog, so once you have sold it, that is it (unless you can convince a fellow player to part with theirs).