A Fortnite player wondered why there was'mold" in their game. Turns out it's texture Tim Sweeney created for Unreal Engine back in 1995

There's an emerging field I call "digital archeology": the excavation and analyses of strange artifacts buried in decades-old programs or websites that are archived. Sometimes, these artifacts rise to the surface by themselves, as in the case of an image of "mold", which was spotted on the news feed for Fortnite by a player.

In response to a question from M1das, Tim Sweeney, founder and CEO of Epic Games, said that the picture is not of mold but a "stock photo" of "cave Pearls, a type of calcium carbonate deposit which forms in limestone caverns."

Sweeney claims he added texture to the Unreal Engine first version in 1995.

"This is Unreal Engine default texture," he said. "I imported it in Unreal Engine 1 back in 1995, when I was developing with a Pentium 90 MHz. It's still in the engine and appears when a programmer fails to specify a texture.

I assume that I've seen these cave pearls a lot: I've played many Unreal Engine games and whoever messed Fortnite's News Feed is not the first developer to forget a texture. I don't know the image. Not like the missing texture icon of the Source engine, that famous fuchsia-checkerboard, or even its giant red "ERROR".

Unreal's default textures are so ambiguous that I may have forgotten them. They look like blobs. Unreal developers haven't forgotten it. Last year, an ILM Immersive artist said that the image "haunts my dreams".