Null Island is a fictional island in the Gulf of Guinea located where the equator crosses the prime meridian, at coordinates 0°N 0°E. Creating null island related things has been an ongoing joke in the geo community. For two years in a row (2015-16), I created t-shirts and stickers (these are very popular and highly coveted) that Mapzen gave out at conferences and events.
Although intended humorously, the fiction has a serious purpose and is used by mapping systems to trap errors. Such errors arise, for example, where an image artifact is erroneously associated to the location by software which cannot attribute a geo-position, and instead associates a latitude and longitude of "Null,Null" or "0,0". Null Island was developed as an idea in 2011 or slightly earlier. Since then, numerous web pages have documented this fictional landmass's flag, geography, and history.
Null island buoy stickers
I designed the null island buoy graphic with inspiration of the red buoy that floats at 0°N 0°E. Since then, this buoy has made appearances in animations and become the official icon of the twitter handle.
The graphic is available under Creative Commons license to use and share.