Minecraft wiki entry for Animation_placeholder_texture, associated text: A second copy of the lava texture was added in the 20100110 Indev build, presumably for flowing lava, despite flowing lava not appearing visually distinct from still lava until the 20100616 build of Infdev. Whether this even represents where flowing lava would be at all, or if versions before 20100110 and inclusively after 20091223-1 would use the same placeholder texture for would-be "flowing" lava (in an identical situation to water) as it would still lava or if it would use the texture at this position instead which was a duplicate of the top of grass at the time, is currently unknown.