Four years of GTA 5 alien mysteries later and the truth may finally be here. The enigmatic alien egg is obtainable in the game via a supply run mission in GTA Online, and collecting it seems to do… nothing special, actually. Seasoned data delvers The Chiliad Mystery Guru Team managed to dig into the code for GTA Online and trigger the mission (check their Reddit thread for more details), and you can watch the whole thing right here. Skip to 5 minutes in if you just want to see the eerie stuff.
That big crashed UFO definitely wasn't there before. Unfortunately, you can't seem to go in it or anything; you just grab the egg, fight off a wave of teleporting aliens (they look like the same ones you encounter in GTA 5 Story Mode's bad trip side missions), then drive it back to your secret base. For now, it seems like nothing else happens, and there's no additional alien stuff in story mode itself.
So yeah, a bit anticlimactic. Rockstar could expand the alien plotline in the future, of course - maybe the egg will hatch in your base and you'll have to go looking for the creature. That would be a great excuse to add a new flamethrower weapon. Or maybe this was just Rockstar's low-key way of tying a bow on the mystery hunt, without returning to its seemingly abandoned plans for story DLC.
While the gurus keep a close eye on any new GTA 5 updates, all we can do is watch the skies… and wonder whatever happened to that GTA 5 single-player DLC in the first place.