Minecraft wiki entry for Wall, associated text: First ever released image of cobblestone walls by Jeb.
An official image by Dinnerbone using beds (and cobblestone walls) to indirectly point to the ending URL of an Imgur image, used to reveal dye-able leather armor.
Cobblestone walls raise at corners and when a block is placed above.
The new walls added on the Village and Pillage update.
A stacked prismarine wall as it appeared up through 1.15.2.
A stacked prismarine wall in 20w06a without gaps.