Two notable Fortnite theories claim to predict the rest of the movement path for the mysterious cube that randomly appeared in-game 11 days ago.
The cube has been on the move since it first zapped into the desert biome, and its slow migration sees it turn on one side every so often. At one point the cube moved every hour and 43 minutes but now its movements are irregular. On two occasions, the cube left a mysterious rune in the ground with a surrounding field of anti-gravity. A third rune is likely to appear today.
Source: IGN.com Fortnite: Cube Movement Theories and Season 6 Speculation Is Running High Among Avid Fans