A mystery continues to develop in Fortnite since Saturday’s rocket launch. Portals appeared across the island at certain locations, and after several hours of glowing in one location, the rifts would expand and then explode, causing an object to disappear. The latest area where this phenomenon took place is a specific spot in Greasy Grove.

A portal showed up on the Durr Burger sign on Wednesday. Players came to see the rift pulsate within the giant burger advertisement and then, the portal grew for a few seconds to then explode with a bright light Thursday. It, along with the giant burger, vanished.

Durr Burger’s sign is the fourth to vanish due to a portal. The first was a sign at Lonely Lodge, which showed up right after Saturday’s rocket launch that caused the sky to crack. It soon disappeared, and then it was a motel sign near Anarchy Acres that also vanished. Afterward, the Mr. Tomato Head in Tomato Town also went bye-bye because of a portal.

The current popular theory to explain the Fortnite portals is time travel. The one-time event was a plan by the season’s antagonist to try and return home. It failed, thus creating a crack in the sky and causing portals to appear. When Season 4 ends, the entire island will go back in time, which is backed by leaked images found by data miners.

A new Fortnite portal has yet to be found, but once it does show up, it will disappear the following day. This will likely continue happening until the end of Season 4 when Epic shows its cards on what players will experience when Fortnite: Battle Royale Season 5 begins.

If exploring the strange sites on the island does not sound appealing, Fortnite players can also spend some time in the Playground Limited Time Mode, which will only be around until July 12.