Dead by Daylight may have four different currencies, but only one asks you to splash the cash - and that's the Auric Cells.
The Auric Cells are bright, yellow-coloured cells that are different from Rift Fragments, Bloodpoints, and Iridescent Shards. The only similarity that they share with Iridescent Shards is that they can be used to buy cosmetics, Survivors and Killers. Other than that, they're completely different.
What are Auric Cells in Dead by Daylight?
Lore-wise, Auric Cells are seen as the building blocks that make up the different realms of the game. This includes the maps, as well as the campfire which Survivors go to after a match.
But what they are gameplay-wise is a currency that can be used to buy things. Namely, cosmetics, characters, as well as the premium section of the Rift Pass that comes with each new Tome released.
How to get Auric Cells in Dead by Daylight
Auric Cells are unable to be earned in any other way outside of dipping into your pocket and grabbing cash from your wallet. Unfortunately, unlike Iridescent Shards, you're unable to earn Auric Cells without real money.
However, if you play Dead by Daylight on mobile then it is possible to earn Auric Cells by progressing through your Player Account Level or by finding packs of Auric Cells in your Bloodweb, via Mystery Boxes.