Minecraft wiki entry for Unused_textures, associated text: In 20w49a, these two textures were added to the assets/minecraft/textures/blocks directory. The top texture is a translucent version of the block of amethyst texture, where the side texture is composed of the sculk sensor's side texture overlayed on the amethyst texture. Interestingly, the amethyst textures are based on those from 20w45a, despite these textures being added in 20w49a after the amethyst block textures were redone twice, implying these textures come from a probably long-since-scrapped functionality of the sculk sensor coupled with amethyst.