Wikipedia explains that the "nurikabe is a yokai, or spirit, from Japanese folklore. It manifests as a wall that impedes or misdirects walking travelers at night. Trying to go around is futile as it extends itself forever. Knocking on the lower part of the wall makes it disappear." It's also the inspiration for Super Mario's Whomp. You can see more photos at Andrew Bell's site or Flickr gallery. And you can buy a painting or print of the Nurikabe at Bear and Bird Boutique. Via I Heart Cool Stuff.
*Previously: Andrew Bell's Zombie Lego Minifig.