The six-limbed man on the wall appears to be a bizarre image by a graffiti artist.

Then it comes alive, scurrying across the wall, transforming into other creatures -- some human, some that can only be described as "other." They veer onto the sidewalk, scatter real twigs and stones, plunge into urban caves, or morph into hideous new beings that devour everything from human heads to office papers...

These are the creations of Italian graffiti artist BLU. And like these creatures, BLU's work also mutates, in this case from one medium to another.

In his mesmerizing film "Muto," BLU painstakingly combines his larger-than-life drawings -- monstrous in all senses of the word -- with stop-motion animation. The film also captures passersby, oblivious to the graffiti that's part of someone else's nightmare. Originally spawned on the walls of Baden, Germany and Buenos Aires, Argentina, "Muto" can now be found on the walls of Vimeo and YouTube.

Like many graffiti artists, BLU declined to be interviewed, preferring anonymity and having his work speak for itself. His website also combines multiple forms of media: photos, sketches, videos and just a touch of animation. But it's "Muto" that haunts viewers, who might now look twice at any street art they encounter -- particularly if it contains more than the usual number of limbs.

For more info visit blublu.org or blublu.org/blog.