Cogito, ergo sum
Unrealed Default Texture
From Unreal Wiki, The Unreal Engine Documentation Site
Have you ever wondered what that greenish bubbly texture in unrealed (Render.utx) is? It turns out to be a real life thing: Cave Pearls. As the name suggests, it's found in caves and it's made of calcite.
I have no idea how that texture ended up as being the default texture in unrealed prior do UE3, but it's nice know what that strange texture is.