Alien Artefacts are a new resource currency in Fortnite Season 7, which can be obtained within matches.
During each match in Season 7, you’ll be able to earn alien artefacts in certain locations across the island or inside cosmic chests. Once you have enough, you’ll be able to spend them into a new customizable alien character called Kymera.
It’s worth keeping in mind that, while during the start of the season Alien Artefacts became available on Tuesdays, they’re now appearing on Thursdays alongside Epic Quests.