Minecraft wiki entry for Unused_textures, associated text: The addition of this texture to terrain.png roughly coincides with Notch mentioning an attempt to add coral blocks to the game, according to a post on The Word of Notch documenting a failed attempt to draw a realistic-looking coral block texture.[7] The texture's hyperbolic appearance does in fact resemble the early iterations of coral blocks showcased at Minecon in 2017.